A. History and Development of the Company Overview We were incorporated as a public, mixed capital company of unlimited duration on September 6, 1973, under the laws of the Federative Republic of Brazil. In 1994, we were registered with the CVM as a publicly held company and are therefore subject to CVM’s rules, including those relating to the periodic disclosure of extraordinary facts or relevant events. Our common shares have been listed on the B3 under the ticker “SBSP3” since June 4, 1997. In 2002, we joined the Novo Mercado segment of the B3 and registered our common shares with the Securities and Exchange Commission (“SEC”) and started trading our shares in the form of ADR - level III on the New York Stock Exchange (“NYSE”) under the ticker “SBS.” Until June 2024, the State of São Paulo owned a majority of our voting common shares. In July 2024, we were privatized, and the State of São Paulo ceased to be our controlling shareholder. As part of our Privatization, Equatorial S.A. became a reference shareholder holding 15% of our voting capital. In accordance with our amended bylaws, we no longer have a controlling shareholder: our bylaws prohibit any shareholder or group of shareholders from exercising votes over 30% of our issued and outstanding voting capital or from entering into shareholders’ agreements for the exercise of voting rights in excess of 30% of our issued and outstanding voting capital. We are subject to Brazilian Corporate Law and to any and all laws and regulations that govern Brazilian private legal entities. We are registered with the Commercial Registry of the State of São Paulo (Junta Comercial do Estado de São Paulo) under registration number NIRE 35300016831. Our principal executive offices are located at Rua Costa Carvalho, 300, Zip Code 05429-900 São Paulo, SP, Brazil. Our telephone number is +55 11 3388-8110. Our agent for service of process in the United States is CT Corporation System, with offices at 818 West Seventh Street - Team 1, Los Angeles, CA 90017. As of December 31, 2025, we provided water and sewage services to numerous residential, commercial and industrial consumers, as well as various public entities, in 375 municipalities in the State of São Paulo, including the city of São Paulo, under concession agreements, with 371 covered by URAE 1 until 2060. Since December 2023, we operate water and sewage services in Olímpia, a municipality located in the interior of the State of São Paulo, through our wholly-owned subsidiary Sabesp Olimpia S.A. This new contract with the municipality of Olímpia is the first bidding process won without being part of a consortium under the New Legal Framework for Basic Sanitation. In May 2025, we exercised our preemptive rights to acquire the remaining 70% equity interests in Águas de Andradina S.A. and Águas de Castilho S.A., which were previously held by Iguá Saneamento S.A. (“Iguá”). Following regulatory review, on July 1, 2025, the Superintendence of Brazil’s Administrative Council for Economic Defense (“CADE”) approved the transaction without restrictions. 35 Table of Contents However, the transaction is still subject to the fulfillment of customary conditions precedent, and therefore the closing has not yet occurred. As a result, we will only consolidate 100% ownership of both concessions after the closing, once all pending conditions have been implemented. We believe that this transaction will strengthen our operational footprint and service delivery capacity in the State of São Paulo. In addition, we maintain a strategic partnership in SESAMM – Serviços de Saneamento de Mogi Mirim S.A., a sewage-only concession, further broadening the scope of our sanitation services. In the basic sanitation sector, we are non-controlling shareholders in two special purpose companies: Aquapolo Ambiental S.A., supplying industrial reclaimed water to the Capuava Petrochemical Complex since 2012 and Attend Ambiental S.A., providing non-domestic wastewater treatment services in the São Paulo metropolitan area since 2014. We also participate in the electric power generation sector through minority partnerships. Through Paulista Geradora de Energia (“PGE”), we leverage the hydraulic potential of the Cantareira System, generating and selling 4.1 MW from the PGE Guaraú plant (operational since March 2023) and 2.9 MW from the PGE Cascata plant (operational since April 2024). Since October 2022, we have held a 49% equity interest in Cantareira SP Energia S.A., a company organized for the development, production and commercialization of photovoltaic energy. Cantareira SP Energia S.A. is also authorized to engage in the commercialization, purchase and sale of energy; the lease, lending for use (comodato) or lease (arrendamento) of assets owned by it or by third parties; the operation and maintenance of power generation facilities; and the acquisition of equity interests in other companies. Since December 2022, we have held a 20% equity stake in Barueri Energia Renovável S.A., a special purpose company designed to process municipal solid waste from the municipality of Barueri and surrounding municipalities into energy. The plant is expected to commence commercial operations in February 2027. In addition, we established SPE Infranext Soluções e Pavimentação S.A., with the purpose of operating in the cold asphalt commercialization and related products segment. However, the entity is currently in its preoperational phase. Recent Developments US$1,500 Million Loan Agreement and US$1,350 Million Blue Bond Issuance On January 27, 2026, we entered into a loan agreement with the Inter-American Investment Corporation, consisting of (i) a senior unsecured loan in an aggregate principal amount of US$150.0 million, issued in a single tranche and maturing in 2038 (the “Term Loan A”), and (ii) a blue unsecured loan in an aggregate principal amount of US$1,350.0 million, issued in two tranches maturing in 2031 and 2036, respectively (the “Term Loan B” and, together with the Term Loan A, the “Loans”). The Term Loan B serves as the underlying asset for the issuance of two series of blue senior secured notes by Nova Securitisation S.À.R.L, including a US$850.0 million in aggregate principal amount of 5.750% blue senior secured notes due 2031, and a US$500.0 million in aggregate principal amount of 6.500% blue senior secured notes due 2036 (“Blue Bonds”). The Blue Bonds are listed on the Euro MTF Market of the Luxembourg Stock Exchange. The Blue Bonds were offered solely to qualified institutional buyers in the United States under Rule 144A and to eligible purchasers in other jurisdictions (excluding Brazil and the U.S.) under Regulation S of the U.S. Securities Act of 1933, as amended. The offering and sale of the Blue Bond were completed on February 3, 2026. We intend to use the net proceeds from the Loans and the Blue Bonds for projects supporting our universalization targets for basic sanitation in the Brazilian state of São Paulo, including construction and upgrading of sewage treatment facilities and expansion of collection systems. Offering and Sale of Debentures On February 10, 2026, we completed our 38th issuance of simple, non-convertible, unsecured debentures, with an aggregate principal amount of R$6,292.1 million, in five series, including: (i) a first series with an aggregate principal amount of R$1,635.7 million, bearing interest at the IPCA index plus 6.2907% p.a., maturing in February 2036; (ii) a second series with an aggregate principal amount of R$1,364.7 million, bearing interest at the IPCA index plus 6.3507% p.a., maturing in February 2038; (iii) a third series with an aggregate principal amount of R$1,291.7 million, bearing interest at the IPCA index plus 6.2467% p.a., maturing in February 2041; (iv) a fourth series with an aggregate principal amount of R$1,000.0 million, bearing interest at CDI index plus a spread of 0.64% p.a.; and (v) a fifth series with an aggregate principal amount of R$1,000.0 million, bearing interest at CDI index plus a spread of 0.72% p.p. 36 Table of Contents These debentures were offered and sold in Brazil exclusively to professional investors (investidores profissionais), as defined under applicable CVM regulations. We intend to use the net proceeds from this offering and sale of debentures for investments related to the universalization and working capital. EMAE Acquisition On October 4, 2025, we entered into certain share purchase agreements, whereby we agreed to purchase: (i) 74.9% of the common shares of Phoenix Água e Energia S.A. of EMAE – Empresa Metropolitana de Águas e Energia S.A. (“EMAE”), held by Vórtx Distribuidora de Títulos e Valores Mobiliários, Ltda., in its capacity as trustee (agente fiduciário) for the holders of certain debentures, subject to certain conditions precedents (“EMAE Control Acquisition”); and (ii) 66.8% of the preferred shares of EMAE, held by Centrais Elétricas Brasileiras S.A. – Eletrobrás (“Eletrobrás”), subject to certain conditions precedent (“EMAE Preferred Shares Acquisition” and, together with the EMAE Control Acquisition, the “EMAE Acquisition”). On January 21, 2026, we completed the EMAE Control Acquisition at a price of R$62.00 per common share, for an aggregate purchase price of R$682.6 million, thereby becoming the controlling shareholder of EMAE. As a result, on February 2, 2026, we filed with the CVM a request for registration of a mandatory tender offer (oferta pública de aquisição de ações) to acquire up to all free float common shares of EMAE, at a price of 49.47 per common share (subject to adjustments based on the Selic rate). ("Tender Offer for the Sale of Control") In addition, on January 28, 2026, we completed the EMAE Preferred Shares Acquisition, at a price per preferred share of R$32.07, totaling an aggregate amount of R$476.5 million, and became holders of 70.1% of the total share capital of EMAE. In addition, on March 12, 2026, we entered into certain quota purchase and sale agreement with África Fundo de Investimento Multimercado Responsabilidade Limitada for the acquisition of 100% of the quotas of Oceania Fundo de Investimento em Ações (“Oceania”), for a total purchase price of R$171.6 million, paid in cash on March 13, 2026. As of the date of this annual report, we hold 79,31% of EMAE's the total share capital and 98.04% of its voting share capital, including the stake in the Oceania acquired on March 12, 2026 as mentioned above. As a result of the increased ownership due the acquisition of the quotas of Oceania, Sabesp requested, on April 24, 2026, CVM approval for the unification of the Tender Offer for the Sale of Control with an tender offer for increase of shareholding (collectively, the “Unified Tender Offer”) to acquire up to all free float common shares of EMAE, at a price of R$61.83 per common share (subject to adjustments based on the Selic rate). EMAE Acquisition represents a strategic milestone for us, delivering benefits on two complementary fronts: • Water security. The integration of the Guarapiranga and Billings systems will provide greater flexibility in water resource management within the São Paulo Metropolitan Region, enhancing water supply security and enabling multiple uses of these water sources; and • Power Assets. EMAE’s portfolio of power generation assets is supported by long-term, inflation-indexed revenue contracts, providing stable cash flows and contributing to financial stability and sustainable value creation. 37 Table of Contents Potential Merger of Shares of EMAE On April 24, 2026, we announced that our and EMAE's respective managements are evaluating the feasibility of a merger of shares of EMAE, pursuant to Article 252 of Brazilian Corporate Law (the “Share Merger”). The feasibility study for the Share Merger includes an analysis of the authorizations, conditions and procedures required for its implementation, as well as the establishment of independent committees to negotiate the share exchange ratio, in accordance with the guidance set out in CVM Guidance Opinion No. 35/2008. If the Share Merger is approved by the management bodies and shareholders of both companies, EMAE will be converted into our wholly owned subsidiary and EMAE’s shareholders will receive shares issued by us in exchange, in accordance with the share exchange ratio to be negotiated by the independent committees. The proposed Share Merger is intended to simplify and optimize the corporate structure of the companies by consolidating their shareholder bases into a single company and reducing operational costs. Acquisition of Sanessol On January 27, 2026, we entered into certain share purchase agreement with Iguá for the acquisition of common shares representing 90% of the capital stock of Saneamento de Mirassol – Sanessol S.A. (“Sanessol”). This acquisition is aligned with our strategy to expand and consolidate our operations in the sanitation sector in Brazil, consistent with our focus on the provision of public water supply and sewage services. The closing of the transaction is subject to the satisfaction of conditions precedent that are customary for this type of transaction. Sanessol’s corporate purpose is the provision of public water and sewage services, and it is the holder of the concession agreement for the operation of the public water supply and sewage services in the municipality of Mirassol, in the State of São Paulo, serving a population of approximately 65,000 inhabitants. Capital Increase On March 16, 2026, our Board of Directors approved an increase in our share capital within the authorized capital limit, by capitalizing profit reserves in the amount of R$169.2 million, through the issuance of 1,132,937 new registered, book-entry common shares with no par value. These new shares were allocated to shareholders of record as of the close of business on March 19, 2026, at a ratio of 0.00160980322 new common shares for each common share held. Prior to this capital increase, our share capital amounted to R$21.2 billion. As a result of the approved transaction, our share capital increased to R$21.4 billion, currently divided into 704,906,805 common shares and one special class preferred share. Approval of Our Share Split On April 28, 2026, our shareholders approved the split all of our outstanding common shares at a ratio of 1:5, so that each one common share will be represented by five common shares, without any change to our share capital (the “Share Split”). The Share Split will not affect our ADR program or the ratio between our ADRs and our common shares. However, following the Share Split, each one ADR will be represented by five ADRs. The Share Split will not result in any change to our shareholders’ proportional ownership interests in our share capital. The common shares resulting from the Share Split will grant their holders the same rights currently attributed to our existing common shares, including with respect to the receipt of dividends, interest on equity and any other distributions that may be approved by us. The implementation of our Share Split is expected to occur on or about May 4, 2026. As a result of the Share Split, the weighted average number of shares considered for the calculation of basic and diluted earning per share presented in our 2025 Consolidated Financial Statements was retrospectively adjusted for all periods presented therein, in accordance with IAS 33. For additional information, see Note 33 to the 2025 Consolidated Financial Statements included elsewhere in this annual report. Our Strategy Our strategy is to provide people a better future by delivering essential services with excellence and a firm commitment to public health and the environment. Our aspiration is to become a global leader in basic sanitation, driving a more sustainable society and generating robust, long-lasting value for our shareholders. To achieve this aspiration, we have defined the following strategic priorities: • Universalization under the new concession agreement for URAE-1 • Customer satisfaction • Stakeholder engagement and support • Water resource sustainability and product quality • Community sustainability • Innovation and digital transformation 38 Table of Contents • Business efficiency • Excellence in regulatory management • Employee development • New business development These strategic priorities define the avenues through which we execute our corporate strategy, guiding resource allocation, capability building, and operating discipline to deliver sustainable value for society and our shareholders. Corporate Organization Following our Privatization and the changes to our bylaws, we updated our governance structure. Key changes included reorganizing departmental responsibilities of each executive officer and creating new structures to optimize our growth and adapt to recent regulatory changes in the sanitation sector. Our executive management currently comprises eleven officers with responsibilities allocated by the Board of Directors and our by-laws. This includes overseeing compliance and risk management, led by a statutory officer appointed by the Board, as well as administrative oversight of internal audit. Statutory Executive Officers: • Chief Executive Officer; • Chief Financial and Investor Relations Officer; • Chief Engineering Officer; • Chief Operation and Maintenance Officer; • Chief Customer and Technology Officer; • Chief Regulation and Power Procurement Officer; and • Chief Legal Officer. Non-statutory Executive Officers: • Chief People Officer; • Chief Corporate Services Officer; • Chief Institutional Relations and Sustainability Officer; and • Chief New Business and Projects Officer. Capital Expenditure Program Our capital expenditure program aims to enhance and expand our water and sewage system, striving for universal sanitation services in the municipalities we operate. It focuses on ensuring water security, meeting the increased demand for treated water in the State of São Paulo, improving operating efficiency and reducing environmental impacts. To achieve this, our investment plan is structured around four pillars: • Expansion Capital Expenditures: focused on meeting the goals of universalization of water supply, sewage and sewage treatment. • Renewal Capital Expenditures: intended for the maintenance of our existing assets. 39 Table of Contents • Operational Efficiency Capital Expenditures: aimed at increasing efficiency, automation and reducing water losses. • Indirect Capital Expenditures: directed to administrative investments and to support our infrastructure. As of the date of this annual report, we anticipate investments of approximately R$70 billion from 2024 to 2029, financed by own resources, loans, and long-term financing. We invested R$15.2 billion, R$6.9 billion and R$6.3 billion in the years ended December 31, 2025, 2024 and 2023, respectively. The following table presents the number of incremental connections achieved in 2025, as well as the targets established for 2026, relating to water coverage, sewage coverage, and sewage treatment. Incremental Connections 2024-2025 (in units) 2026 (in units) Water coverage 435,844 860,860 Sewage coverage 588,427 1,122,272 Sewage treatment 1,027,620 2,121,043 Our capital expenditure program from 2025 through 2029 will continue to focus on achieving our targets by making regular investments to maintain and expand our infrastructure and to reduce water losses in the 375 municipalities we served as of December 31, 2025. Main Focus of Our Capital Expenditure Program The following is a description of the main focuses of our capital expenditure program. Investments in water Expansion of Water Systems: Investments aimed at expanding the supply infrastructure in urbanized areas of the municipalities, in rural communities and in vulnerable communities and informal areas, ensuring the availability of safe and sustainable drinking water to keep up with growths in population, urban development and the growing existing demand, including the implementation of networks, formalization of connections and alternative solutions adapted to the local reality and also new distribution networks, reservoirs, pipelines and reinforcements in existing systems or, for rural areas, well drilling, implementation of simplified systems and decentralized supply technologies. Water Resilience: Continuity of our actions to ensure water security in face of extreme weather events, prolonged droughts, and increased demand. These investments include diversification of water sources, interconnection of systems, expansion of reservoirs and modernization of operational processes. Vegetative Growth: Gradual expansion of our supply infrastructure to meet the increase in population and the verticalization of municipalities we cover. These investments provide for reinforcements in production and distribution of water, ensuring continuity and quality of supply. Investments in sewage Expansion of Sewage Systems (Coverage and Treatment): Investments focused on at expanding the sanitary sewage infrastructure in vulnerable communities and informal areas to ensure viable technical solutions that are appropriate to the local reality, as well as in the expansion of collection networks, connection of new economies and expansion of the installed capacity of sewage treatment plants in urban areas of the municipalities, aiming to serve new residences and promote the reduction of the environmental pollution load of the receiving bodies. For rural areas, these investments are aimed at bringing sewage collection and treatment to rural communities, using appropriate technologies such as septic tanks and compact treatment stations. 40 Table of Contents Vegetative Growth: Expansion of sewage networks and treatment capacity to keep up with the demographic growth of cities. These investments provide for new collection networks, interceptors and modernization of treatment plants to ensure the universalization of sanitation. Loss Reduction Implementation of measures to reduce infrastructure damages or losses (including leaks, pipe ruptures, etc.) and losses arising from consumer fraud (under-metering and other methods of tampering with our measurement devices) in the water distribution system. Our actions include the sectorization of distribution networks, therefore segmenting extensive networks into smaller sections, enhancing the management and operational oversight of the distribution system, replacement of old pipes, replacement of water meters, modernization of measurement methods and combating irregular sewage or water networks. Automation Digitalization and modernization of our operating systems in order to increase our efficiency and reduce costs. Our actions include using telemetry, smart sensors, remote control of pumping stations and implementation of operational control centers to optimize the management of sanitary supply and sewage. Public Information The SEC maintains an internet site (www.sec.gov) that contains reports, proxy and information statements, and other information regarding issuers that file electronically with the SEC, including us. See “Item 10. Additional Information—H. Documents on Display.” Our website is ri.sabesp.com.br/en. Information contained on or obtainable through our website is not incorporated into, and does not constitute a part of, this annual report. B. Business Overview Our Operations As of December 31, 2025, we provided water and sewage services to a broad range of residential, commercial, industrial and governmental customers in 375 of the 645 municipalities in the State of São Paulo, including the city of São Paulo, under concession agreements, with 371 covered by URAE 1 until 2060. These 371 municipalities accounted for 99.8% of our gross operating revenues from sanitation services (excluding revenues relating to the construction of concession infrastructure). Four municipalities (Miguelópolis, Quintana, Nova Guataporanga and Olímpia) continue under their pre-Privatization individual contracts. These concession agreements will expire between 2027 and 2053 and accounted for 0.2% of our gross operating revenues from sanitation services (excluding revenues relating to the construction of concession infrastructure) as of December 31, 2025. We also supplied water and sewage treatment services on a wholesale basis to two municipalities in the São Paulo metropolitan region (Mogi das Cruzes and São Caetano do Sul). For more information on these agreements, see Note 10 to our 2025 Consolidated Financial Statements. As of December 31, 2025, our operating revenue amounted to R$38,092.1 million and profit for the period amounted to R$8,462.1 million. Our total assets amounted to R$104,202.8 million and our total equity amounted to R$42,401.1 million. We provided water services to approximately 29.9 million people, and sewage services to approximately 27.0 million people in the State of São Paulo. For more information on laws and regulations related to our concession operations, see “—Government Regulations Applicable to our Contracts.” 41 Table of Contents Description of Our Activities Our corporate purpose is to provide basic sanitation services aimed at achieving the universalization of basic sanitation in the State of São Paulo. Our primary activities include water supply, sanitary sewage services, urban rainwater management and drainage services, urban cleaning services, and solid waste management services. Our related activities include the planning, operation, and maintenance of systems for the production, storage, conservation and commercialization of energy, as well as the commercialization of services, products, benefits and rights that directly or indirectly arise from our assets, operations and activities. Additionally, at the General Shareholders’ Meeting held on April 29, 2025, our shareholders approved an amendment to our bylaws to include the generation of electricity for self-consumption, with the option to sell any surplus. This amendment is intended to enhance the efficiency of our basic sanitation services and optimize the use of our assets. For more information, see “—Government Regulations Applicable to Our Contracts—ARSESP.” We set forth below a description of our activities. Water Operations Our supply of water to our customers generally involves water extraction from various sources, subsequent treatment and distribution to our customers’ premises. For the year ended December 31, 2025, we produced approximately 3,227.3 million cubic meters of water. The following table sets forth the volume of water that we produced and invoiced for the periods indicated: Year ended December 31, 2025 2024 2023 (in millions of cubic meters) Produced: Total 3,227.3 3,086.3 2,985.2 Invoiced: Residential 1,968.1 1,970.7 1,918.0 Commercial 195.5 191.3 189.2 Industrial 34.2 36.3 35.4 Public 55.2 51.1 47.1 Total Retail 2,253.0 2,249.7 2,189.7 Wholesale (1) 34.9 49.5 46.5 Total 2,287.9 2,299.3 2,236.2 (1) Wholesale includes volumes of reuse water and non-domestic sewage. Seasonality Although seasonality does not affect our results in a significant way, in general, we observe higher water demand during the summer and lower water demand during the winter. The summer coincides with the rainy season, while the winter corresponds to the dry season. The demand in the coastal region is increased by tourism, with the greatest demand occurring during the Brazilian summer holiday months. Water Resources Our water withdrawals are limited to authorized volumes by SP Águas, with federal approval from the National Water and Sanitation Agency (Agência Nacional de Águas e Saneamento Básico - ANA) required for basins crossing state lines. We primarily source our water supply from rivers and reservoirs, with a small portion from groundwater. Our reservoirs are filled by impounding and/or diverting river flows. For more information on water usage regulation, see “—Environmental Matters—Water Usage.” As of December 31, 2025, we operated eleven water systems in the São Paulo metropolitan region. The total capacity of the water sources available for treatment in this area is 1.945 million m3. The average monthly production was 70.7 m3/s, with the Cantareira, Guarapiranga and Alto Tietê systems providing approximately 80% of the water distributed. The Cantareira system alone supplied 41.2% of region’s water. For more information, see “Item 3.D. Risk Factors—Risks Relating to Environmental Matters and Physical and Climate Transition Risks— Droughts, such as the 2014 – 2015 water crisis, can cause a material impact on consumption habits and, consequently, on our business, financial condition or results of operations.” 42 Table of Contents We participate in the decentralized and integrated management of water resources established by the National Policy on Water Resources. We are represented by our employees in all River Basin Committees in the State of São Paulo. The following table sets forth the water production systems from which we produce water for the São Paulo metropolitan region: Year ended December 31, 2025 2024 2023 (in cubic meters per second) Water production system: Cantareira 29.1 28.7 26.5 Guarapiranga 13.4 12.4 13.1 Alto Tietê 12.6 12.9 12.4 Rio Claro 3.3 4.7 3.5 Rio Grande (Billings reservoir) 5.1 3.0 4.6 Alto Cotia 1.0 1.0 1.0 Ribeirão da Estiva 0.0 0.1 0.1 São Lourenço 5.2 4.0 3.3 Cabuçu and Tanque Grande (Guarulhos) 0.2 0.3 0.3 Embú-Guaçu 0.1 0.1 - Total 70.7 67.2 64.8 Water Treatment As of the date of this annual report, we operate 214 water treatment facilities and 690 simplified water treatment facilities, where all water is treated before being distributed by our water supply network. The type of treatment used depends on the nature of the source and quality of the untreated water. For example, water abstracted from rivers requires more treatment than water withdrawn from groundwater sources. All of the water we treat receives fluoridation. Water Distribution We distribute water through our networks of water pipes and water transmission lines. Storage tanks and pumping stations regulate the volume of water flowing through the networks in order to maintain adequate pressure and continuous water supply. The following table sets forth the number of connections in our network as of the dates indicated: As of December 31, 2025 2024 2023 Number of connections (in thousands)(1) 10,624 10,455 10,286 (1) Includes the connections from URAE-1, Miguelópolis, Nova Guataporanga, Quintana, and Olímpia. Water Loss Water loss is calculated as the difference between the volume of water produced and the volume of water measured by the water meters installed in our customers’ properties. Water losses are divided into: apparent (non-physical) losses, which result mainly from inaccurate water meters, fraud and registration errors, and real (physical) water losses, resulting from leaks in the distribution network and overflows in tanks. 43 Table of Contents We exclude from the calculations of water loss: (i) water discharged for periodic maintenance of water distribution lines and cleaning of water storage tanks; (ii) water supplied for municipal uses, such as fighting fires; and (iii) estimated water loss related to the supply of water to urban areas occupied by low-income populations in irregular areas (favelas). Water loss decreased from 34.6% as of December 31, 2012 to 30.5% as of December 31, 2025, as measured by the total distribution losses index (Índice de Perdas na Distribuição, or IPM). In respect of the Concession Agreement for URAE-1, we have met the water loss reduction targets established for 323 municipalities for 2025, as set out in Annex II of the Concession Agreement for URAE-1. Water Quality We believe that we supply high quality treated water that is consistent with the standards set by Brazilian law, which establishes water quality standards (Annex XX of Consolidation Ordinance No. 5 - amended by Ordinance No. 888 of May 2021), requiring us to comply with significant regulatory obligations. In general, the State of São Paulo has excellent water quality. However, there are anthropogenic and natural factors that can cause changes in water quality. Currently, we treat this water to make it potable and we are also investing in improvements in our water transmission lines and our treatment systems to ensure the quality and availability of water for the coming years. Water quality is monitored at all stages of the distribution and is carried out by our quality control laboratories distributed in various regions of the State of São Paulo, equipped with modern analytical equipment and qualified professionals. Our laboratories are ABNT NBR ISO IEC 17025 accredited, awarded by INMETRO. Quality control of the chemicals used in water treatment is also performed to verify compliance with the specifications established in national and international recommendations, aiming to ensure the absence of toxic substances harmful to human health. As of the date of this annual report, we believe that there are no material instances where our standards are not being met. Fluoridation As required by Brazilian law, we add fluoride to the water at our treatment facilities prior to its distribution into the water supply network. Fluoridation primarily consists of adding fluorosilicic acid to water at between 0.6 mg/L and 0.8 mg/L to assist in the prevention of tooth decay among the population. Sewage Operations We are responsible for the collection, removal, treatment and final disposal of sewage. We installed 197.3 thousand, 191.4 thousand and 226.5 thousand new sewage connections in the years ended December 31, 2025, 2024 and 2023, respectively. Sewage System The purpose of our sewage system is to collect and treat sewage and to adequately dispose of the treated sewage. The following table sets forth the total number of sewage connections in our network for the periods indicated: As of December 31, 2025 2024 2023 Sewage connections (in thousands) 9,160 8,932 8,776 Our sewage system is generally designed to operate by gravitational flow, with pumping stations used where necessary, employing cast iron sewage lines. 44 Table of Contents The public sewage system is designed to handle both household and portion non-domestic effluents (such as industrial sewage) which require compliance with specific legal standards to protect the sewage collection and treatment systems, the health and safety of operators and the environment. Non-domestic effluents must meet standards set by State Decree No. 8,468/1976, and may require pretreatment. We conduct acceptance studies to ensure compliance and capacity before permitting discharge, formalizing conditions in agreements with effluent producer. Non-compliance can result in penalties, with CETESB notified for severe breaches. Effluents from our treatment facilities must comply with limitation guidelines for discharge into receiving water bodies, ensuring water quality is not compromised, as established by State Law No. 997/1976 regulated by State Decree No. 8,468/1976 and the National Environmental Council (Conselho Nacional de Meio Ambiente – “CONAMA”) Resolution No. 357/2005, as amended by CONAMA Resolution No. 430/2011 which establishes conditions and standards for effluent discharge. Sewage Treatment and Disposal As of December 31, 2025, we operate 641 sewage treatment facilities, including eight ocean outfalls, with an installed capacity of approximately 61.4 cubic meters of sewage per second. In the São Paulo metropolitan region, the treatment process used by most treatment facilities is the activated sludge process. In other regions, sewage treatment varies according to the particularities of each area. In the interior region of São Paulo State, treatment consists largely of stabilization ponds. The majority of sewage collected in the coastal region receives treatment and disinfection and is then discharged into rivers and also into the Atlantic Ocean through our ocean outfalls, in accordance with applicable legislation. In this regard, we are a party to legal proceedings related to environmental matters. For more information, see “Item 8.A. Consolidated Financial Statements and Other Financial Information—Legal Proceedings.” In addition, our capital expenditure program includes projects to increase the amount of sewage that we treat. For more information, see “Item 4.A. History and Development of the Company—Capital Expenditure Program” and “Item 4.B. Business Overview—Environmental Matters—Environmental Regulation—Sewage Requirements.” Sludge Disposal The generation of sludge is inherent in the sanitation cycle. We use various methods, such as filter presses, belt filter presses, drying beds and centrifugation machines, to dewater sludge, reducing its volume and final disposal costs. We are exploring innovative technological sludge disposal methods. Since 2018, we have produced an agricultural organic fertilizer, Sabesfértil, made by bio-drying sewage sludge, and which was approved for sale by the Ministry of Agriculture. Other projects include a plasma system which uses specialized technology to transform sludge into an inert solid vitreous product to be re-used in construction work, and a sludge dryer that uses sunlight and automated processes. In 2025, we conducted operational tests with a pilot thermal sludge treatment plant using pyrolysis to evaluate byproducts such as biochar, pyrolytic oil and syngas. We are implementing a thermal sludge drying system that uses indirect dryers fed exclusively with biogas generated at the wastewater treatment plant itself. The aim is to convert the sludge into material for agricultural input, reducing the need for final disposal and contributing to the circular economy and the value add of by-products. Sludge disposal must comply with State and Federal law requirements. In the State of São Paulo, CETESB has reissued the technical standard P4,230, second edition, of May 2021, which addresses the “application of sludge from biological treatment systems of sanitary liquid effluents in soil – guidelines and criteria for the project and operation.” This allows sludge use for soil recovery, creating new opportunities in the countryside of the State of São Paulo. 45 Table of Contents Principal Markets in Which We Operate We provide water and sewage services directly to a large number of residential, commercial and industrial consumers, as well as to a variety of public entities. Our Concession Agreements The Concession Agreement for URAE-1 The Concession Agreement for URAE-1 provides for significant changes to our economic-regulatory model. Under the Concession Agreement for URAE-1 we provide services for water and sewage to 371 municipalities in the state of São Paulo. The Concession Agreement for URAE-1 also provides for specific targets such as the Universalization Target. Under the Concession Agreement for URAE-1, the tariff adjustment index (Índice de Reajuste Tarifário - IRT) also provides for significant changes to our Tariff Structure, as defined below. We cannot guarantee that these changes will not have a significant financial impact on us. The main provisions of the Concession Agreement for URAE-1 are as follows: • Adoption of a retroactive methodology for tariff recognition of investments (the tariff calculation will only incorporate the investments already made by us). • Changes of the tariff review equation for the first two cycles of the Concession Agreement for URAE-1, with the inclusion of the Factor U and updates to the regulatory asset base (“RAB”) and market achieved in the reference year. In the first two cycles, the RAB will be updated annually. Additionally, similar to the previous model, inflation, Factor Q and Factor X are considered. • The Factor U will be applied annually as a reducing factor of up to 10% as part of the tariff readjustments. • The WACC will be applied before taxes. • New concepts: the “application tariff” (for service users) and “equilibrium tariff” (to be received by us). The difference will be compensated mainly by FAUSP (created by State Law No. 17,853/2023), which provides resources for basic sanitation actions, including those aimed at tariff moderation in the sector, in order to achieve and the universalization targets for 2029, as set out by State Law No. 17,853/2023. • On a monthly basis, we must calculate the difference between the (i) regulatory revenue effectively received from the market, by applying the application tariff, and the (ii) regulatory revenue, by applying the equilibrium tariff. • The valuation of new investments will be made using the depreciated replacement cost (DRC) method. • The remuneration of regulatory working capital will deduct the earnings from financial investments. • The failure to implement regulatory accounting by 2026 will result in a penalty of 100% of accessory revenues being allocated to tariff moderation and a greater sharing of efficiency with tariff moderation already in the second tariff cycle of the Concession Agreement for URAE-1. • The new model stipulates that we will be entitled to integrate a portion of the efficiency gains they achieve over multiple cycles. • Several parts of the methodology need to be regulated by ARSESP. As of the date of this annual report, we are a party to (i) the Concession Agreement for URAE-1; and (ii) four individual contracts entered into with the municipalities of Miguelópolis, Nova Guataporanga, Quintana, which chose not to join the Concession Agreement for URAE-1, and Olímpia. 46 Table of Contents Competition Competition primarily arises through mandatory public tenders for new or renewed sanitation concessions under Brazil’s updated legal framework (Law No. 14,026/2020), which intensified bidding between state-owned and private operators. Within URAE-1, we serve 371 municipalities under a regional concession; outside that perimeter or in non-adherent municipalities, tenders may occur and we may face competitors or decide to bid ourselves, including beyond State of São Paulo. Additionally, we may participate in competition for other concessions for the provision of water and sewage services in municipalities, metropolitan regions, microregions and regional units outside of the State of São Paulo. Use of Alternative Water Sources In recent years, we have experienced an increasing level of use of alternative sources, including residential condominiums and non-residential, industrial customers. One reason for the use of alternative water sources is because some users require water with different technical specifications than the water made available to the public. This trend has increased in recent years, especially since the 2014-2015 water crisis, when non-residential customers and residential condominiums sought independent solutions to supply water and dispose of non-residential, commercial and industrial sludge in the São Paulo metropolitan region. Private companies offer stand-alone water treatment solutions inside the facilities of their customers. In addition, the treatment of non-residential, commercial and industrial sewage treatment in the São Paulo metropolitan region has increased in recent years as private companies have started to offer customized solutions for customers’ facilities. Competition for new municipalities As described in our bylaws, we may operate through subsidiaries in any part of Brazil or abroad to provide sanitation services. We believe this makes us a potential competitor for other sanitation companies, both Brazilian and foreign. The New Legal Framework for Basic Sanitation imposes mandatory bidding processes for municipalities to hire companies providing basic sanitation services. This opened up a new business environment in which state-owned and private companies could compete. Participating in a bidding process is now the only method of maintaining and/or expanding our market share, whether in the State of São Paulo or in other states. Billing Procedures The billing and payment procedure for our water and sewage services is largely the same for all customer categories. Under the current tariff structure, water and sewage bills are based on water consumption determined by monthly meter readings. Sewage charges are included in the water bill and are based on the water meter reading. Meter readings for billing purposes are taken by our team and/or third parties using a mobile application, with simultaneous printing and delivery of the bill to the customer or, if the customer prefers, the bill can be sent digitally (by email, for example) or by mail to an address of the customer’s choice. Water and sewage bills can be paid online, via PIX (Brazil’s instant payment system), through banking correspondents, or by debit or credit card. Customers must pay their water and sewage bills by the due date to avoid late payment fees and interest. Customers with unpaid bills are subject to administrative collection procedures, water supply disconnection, and legal collection proceedings. The improvement of our collections process was one of the principal drivers of increased EBITDA and cash generation in 2025. We more than tripled the volume of cutoff and collection orders, with all teams equipped with POS (Point of Sale) terminals, enabling customers to make payments on-site to avoid water supply disconnection. 47 Table of Contents We believe we were the first utility in the world to implement payment via WhatsApp using PIX and credit card, including installment payments, and we believe we were the first company in Brazil to implement Automatic PIX (Brazil’s automatic recurring instant payment feature), reflecting our commitment to innovation in the adoption of technology. Furthermore, we intensified the reporting of defaulting customers to credit bureaus, the negotiation of debts with large debtors, and the holding of Debt Negotiation Fairs (“Large credit campaigns”). With these initiatives, we increased our collection rate from 98.1% to 101.7% (a collection rate exceeding 100% reflects the recovery of amounts billed in prior periods), resulting in an increase in cash of approximately R$900 million in 2025, and a reduction in our allowance for doubtful accounts (PECLD) of approximately R$450 million, with a corresponding positive impact on EBITDA. With respect to commercial losses (water fraud, theft, and underreporting of sewage), we launched a Commercial Loss Reduction Program in 2025 to decrease losses through strategies that ensure operational efficiency and financial effectiveness. The actions prioritize optimizing the selection of targets for inspections, increasing revenue, and promptly regularizing losses that impact billing. In 2025, we centralized the administrative activities of the process, promoting standardization and strengthening management: • In 2025, approximately 52,559 irregularities were identified, more than double the number identified in 2024, with approximately the same number of inspections (approximately 212,000), demonstrating greater productivity and operational effectiveness. • This resulted in a significant improvement in our accuracy rate, increasing from 12% in 2024 to 25% in 2025, more than doubling our fraud detection accuracy rate. In addition to identifying more irregularities, we increased our efficiency in revenue recovery, reaching R$75 million in 2025, approximately five times the amount recovered in 2024, reinforcing the economic impact of our anti-fraud actions. Our digital transformation is underway, with several initiatives in progress, including the Electronic TOI (Irregularity Report) and the robotic automation of irregularity calculations through the implementation of RPA (Robotic Process Automation), resulting in approximately 9,000 calculations completed and R$19.5 million recovered within two months of implementation. In 2025, we commenced the modernization of our metering infrastructure, a program that will deploy approximately 4.4 million ultrasonic meters with NB-IoT telecommunications and embedded shut-off valves by 2029. We believe this will make our AMI project the largest Smart Water Metering initiative in the world, promoting operational efficiency, reducing losses and unpaid debts, and empowering our customers to actively manage their water consumption. This solution was developed based on extensive international benchmarking and reflects global best practices in smart water metering. Additionally, we replaced approximately 1.5 million obsolete meters in customer. In aggregate, we estimate that these metering initiatives will generate a net present value (NPV) of over R$8 billion, with an internal rate of return (IRR) ranging between 39% and 52%. Customer Relationship In 2025, customer relationship management maintained its position as a central pillar of our strategy, supporting organizational, digital, and process transformation. The initiatives developed throughout the year focused on making service more agile, expanding access to services, and ensuring increasingly positive interactions with customers, in compliance with the regulations applicable to the basic sanitation sector in the State of São Paulo. Our customer relationship strategy is structured around an integrated approach combining technological modernization, service process redesign, and evolution of management models. Throughout 2025, we worked to reduce barriers in the customer journey, increase the transparency of interactions, and offer faster and more predictable responses, with the goal of strengthening trust and the efficiency of the services provided. 48 Table of Contents We advanced in the digitalization of our relationship channels through the integration of platforms and the expansion of our omnichannel model. Digital channels now play a significant role in transactional service and customer communications, enabling access to information, service requests, demand tracking, and digital payment processing, including via PIX (Brazil’s instant payment system) and credit cards. This process included the modernization of our customer relationship management (CRM) systems through the gradual implementation of the Salesforce platform, as well as the redesign of critical customer journeys and the expansion of functionalities available on digital channels, contributing to the standardization of service and the simplification of processes. We have also expanded the use of automated channels and artificial intelligence-based solutions, including IBM Watson-powered Interactive Voice Response (IVR) systems in our telephone service operations, with the aim of increasing service capacity, reducing average response time, and redirecting human resources to more complex demands. These solutions support the resolution of recurring requests and guide customers throughout the service process, contributing to the efficiency of our channels and reducing demand for in-person and telephone support. Our omnichannel strategy was complemented by the continuous evolution of our mobile application and virtual agency, which consolidated functionalities previously distributed across different channels. In face-to-face and field service, we adopted technological solutions aimed at expanding payment options, with the goal of facilitating debt settlement and reducing operational barriers in customers’ financial interactions with us. In 2025, our customer satisfaction survey, conducted by GRM Pesquisa de Mercado, indicated a satisfaction rate of 82%, compared to 83% for the year ended December 31, 2024. Our net promoter score, which measures customer loyalty and likelihood to recommend our services, was 47 for 2025, compared to 44 for 2024. The results of these indicators are used as inputs for the continuous improvement of our customer relationship policies and processes. The strengthening of customer relationships is linked to our pursuit of operational efficiency and long-term financial sustainability. The integration of technology, processes, and business areas contributes to improved productivity and collection processes, while supporting our long-term objectives related to the adequate, continuous, and universal provision of services. Contract URAE-1 Tariffs Tariffs are our main form of remuneration for the services we provide under the Concession Agreement for URAE-1. Under the Concession Agreement for URAE-1, the tariffs aim to remunerate the investment effectively made and incorporated into the concession’s asset base. There are two tariffs: the application tariff, which is what the user actually pays, and the equilibrium tariff, which is owed to us. Any difference between the application tariff and the equilibrium tariff is covered by FAUSP. Tariff adjustments for our services follow the guidelines established by regulatory standards including the Concession Agreement for URAE-1 and its schedules, especially Schedule V. These guidelines establish procedural steps and the terms for the annual adjustments, which are to be conducted by ARSESP. The approved regulatory model adopted by ARSESP for the Concession Agreement for URAE-1 defines a maximum average tariff (P0), based on the guarantee of the economic and financial balance of the provider, such as us, in its business segment and on efficient costs projected for the tariff cycle, to encourage the provider to permanently seek to reduce its costs. Accordingly, an average tariff is established, expressed in reais per cubic meter, which reflects the economic cost of providing water and sewage services in a tariff cycle of five years. The methodology is based on a backward-looking approach, in which the equilibrium tariff is calculated by building blocks, considering costs, investments and the reference market ex-post to their realization, as observed in the reference period. 49 Table of Contents Within the scope of periodic tariff reviews, the calculation parameters for the tariff components — such as the rate of return (WACC), the X-Factor, and efficient operating costs — will be defined by ARSESP, in accordance with the criteria and methodologies set forth in Annex V – Regulatory Model, which structures all tariff-setting processes. Further to the reviews, the tariffs under the Concession Agreement for URAE-1 are adjusted annually. The tariff adjustment procedure follows the provisions set forth in Annex V and incorporates inflation variation (IPCA price index accumulated over the past 12 months), any deductions resulting from non-compliance with universalization targets (U-Factor) and quality indicators (Q-Factor), as well as the application of an efficiency-sharing factor starting from the 3rd Tariff Cycle (the X-Factor). In addition to inflation and performance mechanisms (U-Factor and Q-Factor), during the first two tariff cycles (2024–2034), annual adjustments will also take into account the reassessment of the equilibrium tariff revenue. This reassessment is intended to update the regulatory asset base and the reference market, in accordance with the formula specified in Annex V of the Concession Agreement for URAE-1. The adjustments cover a 12-month period, except for the first one, which covered the period between the effective date of the Concession Agreement for URAE-1 (July 23, 2024) and December 31, 2025. For all adjustments, December will be used as the base month for regulatory approval, and January 1 of the following year will be the effective date for the application of the updated tariffs, subject to the availability and publication of the official inflation indices. Throughout 2025, the tariffs remained unchanged because the Concession Agreement for URAE-1 established that the tariff schedule set forth in Annex IV would remain fixed until December 2025. As a result, the tariff levels applied from the effectiveness of the Concession Agreement for URAE-1 in July 2024 continued unchanged for the entire 2025 calendar year. For more information, see “Item 3.D. Risk Factors — We are exposed to risks associated with the Concession Agreement for URAE-1, which may materially impact our financial condition and operating results” and “Item 10.F Additional Information – C. Material Contracts — Concession Agreement for URAE-1.” Tariff Structure Our current tariff structure, governed by State Decree No. 41,446/1996 and by the Concession Agreement for URAE-1, is divided into residential and non-residential categories. The residential category is subdivided into standard residential, residential-social, and vulnerable residential tariffs. Social tariffs benefit low-income families, the unemployed, and collective living residences, while vulnerable tariffs support urban areas lacking urban infrastructure. In addition, the tariff structure includes an unmetered rural category, applicable to connections used exclusively in rural units whose service delivery systems differ from those of other categories; the tariff for this category is equal to the fixed charge applied to the standard residential category. The non-residential category consists of: (i) commercial, industrial and public customers; (ii) nonprofit entities that pay 50.0% of the prevailing non-residential tariff; (iii) government entities that adhere to the Rational Use of Water Program (Programa de Uso Racional da Água – “PURA”) and pay 75.0% of the prevailing non-residential tariff; and (iv) public entities that have entered into program agreements, for municipalities with a population of up to 30.0 thousand and with half or more classified according to their degree of social vulnerability by the Social Vulnerability Index of São Paulo (Índice Paulista de Vulnerabilidade Social) 5 and 6, of the SEADE, obtained through the analysis of the 2000 Census figures, which start to receive tariff benefits, in accordance with our normative ruling, for the category of public use, at the municipality level. The tariffs for entities described in item (iv) are equal to those offered to the nonprofit entities mentioned in item (ii) above, corresponding to 50.0% of the public tariffs without contractual provisions referred to in item (iv) above. Social Tariff Update On August 1, 2025, ARSESP Resolution No. 1,699 established the criteria and procedures for classifying users within the Social Residential and Vulnerable Residential tariff categories and introduced the “Tarifa Social Paulista” program. Subsequently, on August 7, 2025, the Second Amendment to Concession Agreement No. 01/2024 was executed, further updating the definitions and tariff structure related to the social tariff program. 50 Table of Contents ARSESP Resolution No. 1,699/2025 and the Second Amendment to Concession Agreement No. 01/2024 did not change the eligibility criteria for the Vulnerable Residential category. However, for the Social Residential category, the resolution and the Second Amendment to Concession Agreement No. 01/2024 expanded eligibility by adding a new criterion for households registered in CadÚnico with per-capita income of up to half the minimum wage that include a person with disabilities or an elderly individual aged 65 or older receiving the federal continuous cash benefit program (Benefício de Prestação Continuada — “BPC”). In addition to the existing Social Tariff and Vulnerable Tariff, which benefit users enrolled in the Federal Government’s Single Registry (Cadastro Único), the program introduced the Social Tariff II category to expand eligibility to users who meet the following criteria: they reside in informal urban settlements (favelas); are included in a regularization program carried out by us; reside in areas characterized by social vulnerability, including informal settlements and low-income urban communities; or live in areas inhabited by indigenous peoples, traditional communities, or rural populations. There are tariff tables with the values due for each consumption pricing range for these categories: up to 10 m³, from 11 to 20 m³, from 21 to 50 m³, and above 50 m³. The “Residential Social” and “Residential Vulnerable” categories have five consumption pricing ranges: up to 10 m³, from 11 to 20 m³, from 21 to 30 m³, from 31 to 50 m³, and above 50 m³. The amount charged is always progressive. Large consumers and municipalities served by wholesale have separate tariff tables. Water and Sewage Services Tariffs Under the current tariff structure, we establish separate tariff schedules for our services in each of the São Paulo metropolitan regions and each of the interior regions of the State of São Paulo and the coastal regions, depending on whether a customer is located in the São Paulo metropolitan region or the interior of the State of São Paulo and in the coastal regions of São Paulo. Each tariff schedule incorporates regional cross-subsidies, taking into account the customer type and volume of consumption. Where tariffs paid by customers with high monthly water consumption rates exceed our costs of providing water services, we use the excess tariff billed to high-volume customers to compensate for the lower tariffs paid by low-volume customers. Similarly, tariffs for non-residential customers are set at levels that subsidize residential customers. In addition, the tariffs for the São Paulo metropolitan region generally are higher than tariffs in the interior region of the State of São Paulo and the coastal regions. In the years ended December 31, 2025 and 2024, the average tariff calculated for the interior of the State of São Paulo and in the coastal regions of São Paulo was approximately 20% below the average tariff of the São Paulo metropolitan region. 51 Table of Contents The following table sets forth the water tariffs by (i) customer category and class; and (ii) volume of water consumed, charged in cubic meters during the years and period stated in the São Paulo metropolitan region: As from July 23, As from July 23, As from May 10, As from May 10, As from May 10, 2025 2024 2024 2023 2022 (in reais) Standard Residential: 0-10(1) 3.80 3.80 3.83 3.59 3.27 11-20 6.01 6.01 6.01 5.62 5.13 21-50 14.98 14.98 14.98 14.00 12.78 Above 50 16.50 16.50 16.50 15.43 14.08 Social: 0-10(1) 1.08 1.08 1.20 1.12 1.02 11-20 2.05 2.05 2.05 1.92 1.75 21-30 7.32 7.32 7.32 6.84 6.24 31-50 10.42 10.42 10.42 9.74 8.89 Above 50 11.51 11.51 11.51 10.77 9.83 Urban areas occupied by low-income populations in irregular areas (favelas): vulnerable social starting in 2021: 0-10(1) 0.82 0.82 0.91 0.85 0.78 11-20 1.03 1.03 1.03 0.96 0.88 21-30 3.45 3.45 3.45 3.23 2.95 31-50 10.42 10.42 10.42 9.74 8.89 Above 50 11.51 11.51 11.51 10.77 9.83 Social II: 0-10(1) 1.90 - - - - 11-15 3.01 - - - - 16-20 6.01 - - - - 21-50 14.98 - - - - Above 50 16.50 - - - - Commercial/Industrial/Governmental: 0-10(1) 7.66 7.66 7.70 7.20 6.57 11-20 14.98 14.98 14.98 14.00 12.78 21-50 28.71 28.71 28.71 26.84 24.50 Above 50 29.90 29.90 29.90 27.96 25.52 Social Welfare Entities: 0-10(1) 3.83 3.83 3.85 3.60 3.28 11-20 7.48 7.48 7.48 6.99 6.38 21-50 14.41 14.41 14.41 13.47 12.29 Above 50 14.97 14.97 14.97 13.99 12.77 Public Entities with contract: 0-10(1) 5.74 5.74 5.77 5.39 4.92 11-20 11.22 11.22 11.22 10.48 9.57 21-50 21.59 21.59 21.59 20.18 18.42 Above 50 22.44 22.44 22.44 20.98 19.15 (1) The minimum volume charged is ten cubic meters per month. Sewage charges in each region are fixed and based on the same volume of water charged. In the São Paulo metropolitan region and the coastal region, the sewage tariffs are equal to the water tariffs. In the majority of the municipalities of the interior region of the State of São Paulo, sewage tariffs are approximately 20.0% lower than water tariffs. Wholesale water rates are the same for all municipalities served in the São Paulo metropolitan region. We provide sewage treatment services to those municipalities in line with the applicable contracts and tariffs. In addition, various industrial customers pay an additional sewage charge, depending on the characteristics of the sewage they produce. Each category and class of customer pays tariffs according to the volume of water consumed. The tariff paid by a certain category and class of customer increases progressively according to the increase in the volume of water consumed. The first tranche (0–10 m³) corresponds to the minimum fee charged to our customers for the consumption of water. 52 Table of Contents Contract SABESP Olímpia S/A Tariffs Public Tender No. 02/2023 awarded SABESP Olímpia a 30-year concession to operate water supply and wastewater services in the Municipality of Olímpia. The concession contract was signed on October 11, 2023, and operations began on December 10, 2023. The tariff defined in the tender process is intended to ensure the economic and financial equilibrium of the concession by covering efficient operating costs, contractual obligations, and required investments. Brazilian legislation guarantees the right to maintain such equilibrium, and the concession contract confirms that it must be preserved whenever contractual conditions are met. The economic and financial equilibrium is determined through a discounted cash flow model that reflects the tariff revenue needed to achieve the internal rate of return accepted in the winning bid, set at 11.88%. The concession provides for both ordinary tariff reviews, conducted every five years, and extraordinary reviews, which may be triggered by events that alter the contractual risk allocation or financial conditions. In addition to these review mechanisms, the tariff and the public prices of complementary services are subject to an annual adjustment, applied every 12 months, based on the accumulated variation of the IPCA. Regulatory Adjustments. ARES-PCJ approved a 9.52% tariff adjustment effective November 17, 2024, covering water and sewage tariffs as well as the public prices for other services, as set forth in Resolution No. 583. On October 21, 2025, ARES-PCJ approved an additional 5.17% adjustment under Resolution No. 659, corresponding to the accumulated IPCA for the period from October 2024 through September 2025. In the same proceeding, ARES-PCJ also approved a 3.27% tariff review to restore the contractual economic and financial equilibrium in light of specific imbalance events, including the implementation of the Residential Social Tariff under Federal Law No. 14,898/2024, set at 8.61%. These adjustments were compounded with the general adjustment and applied on December 4, 2025. Tariff Structure Under the Olímpia Concession Agreement, the tariff structure is organized into residential and non-residential categories, with separate schedules for water and sewage services. The residential category may include sub-categories aligned with social policy instruments defined by the applicable regulatory framework. The non-residential category comprises commercial, industrial, public, and mixed customers. For all categories, charges are assessed by progressive consumption blocks, and the first tranche (0–10 m³) corresponds to the minimum charge, which is billed regardless of actual water or sewage consumption. Large-volume users and specific service modalities may be subject to dedicated tariff tables, as provided for in the concession and the regulator’s rules. Social Tariff Update. Following Federal Law No. 14,898/2024, the criteria and discounts applicable to the Residential Social Tariff in Olímpia were revised to align with the new legal framework. ARES-PCJ updated its rules accordingly, and the revised tariffs and eligibility criteria became effective in early 2025. There are tariff tables with the values due for each consumption pricing range for these categories: up to 10 m³, from 11 to 20 m³, from 21 to 30 m³, from 31 to 50 m³, from 51 to 60 m³, from 61 to 70 m³, and above 70 m³. The "Residential Social" category has eight consumption pricing ranges: up to 10 m³, from 11 to 15 m³, from 16 to 20 m³, from 21 to 30 m³, from 31 to 50 m³, from 51 to 60 m³, from 61 to 70 m³, and above 70 m³. The following table sets forth the water tariffs by customer category, class, and consumption range, expressed in cubic meters, applicable to the Olímpia concession during the periods shown: 53 Table of Contents Customer Category Consumption As from December 4, 2025 As from November 17, 2024 Standard Residential: 0-10(1) 2.53 2.33 11-20 5.09 4.69 21-30 5.16 4.75 31-50 6.40 5.89 51-60 9.24 8.51 61-70 9.37 8.63 Above 70 9.42 8.67 Social: 0-10(1) 1.27 - 11-15 2.55 - 16-20 3.82 - 21-30 5.16 - 31-50 6.40 - 51-60 9.24 - 61-70 9.37 - Above 70 9.42 - Commercial 0-10(1) 3.62 3.33 11-20 6.36 5.86 21-30 6.39 5.88 31-50 7.99 7.36 51-60 9.28 8.54 61-70 9.37 8.63 Above 70 9.42 8.67 Public: 0-10(1) 7.82 7.20 11-20 7.62 7.02 21-30 7.70 7.09 31-50 10.40 9.58 51-60 11.82 10.88 61-70 11.93 10.98 Above 70 12.03 11.08 Industrial: 0-10(1) 7.24 6.67 11-20 7.07 6.51 21-30 7.10 6.54 31-50 9.59 8.83 51-60 10.82 9.96 61-70 10.87 10.01 Above 70 11.01 10.14 Mixed 0-10(1) 3.08 2.83 11-20 5.73 5.28 21-30 5.78 5.32 31-50 7.20 6.63 51-60 9.28 8.54 61-70 9.37 8.63 Above 70 9.42 8.67 (1) The minimum volume charged is ten cubic meters per month. The sewage tariff is equal to 80% of the applicable water tariff. The first tranche (0–10 m³) reflects the minimum charge, assessed independently of the customer’s actual water or sewage consumption. Government Regulations Applicable to our Contracts Basic sanitation services in Brazil are subject to extensive federal, state and local legislation and regulations. From a federal regulatory perspective, the current legal framework for basic sanitation (Federal Law No. 14,026/2020) granted the National Water and Basic Sanitation Agency (ANA) the authority to issue reference standards for how subnational regulatory agencies should regulate the sector. These reference standards cover, among other topics: (i) quality and efficiency standards for the services provided, including the maintenance and operation of basic sanitation systems; (ii) tariff regulation; (iii) standardization of contractual instruments for basic sanitation concessions; (iv) targets for the universalization of services; (v) criteria for regulatory accounting; (vi) progressive reduction and control of water losses; (vii) methodologies for calculating indemnities for investments not yet amortized or depreciated; (viii) governance standards for regulatory entities; (ix) rules regarding the reuse of treated effluents; (x) parameters for determining the termination of service provision; (xi) standards relating to the transition from unitary sewage systems to separate systems; (xii) systems to assess targets for the expansion and universalization of service coverage; and (xiii) minimum standards for full service provision and economic and financial sustainability. 54 Table of Contents Key reference standards issued by ANA to date include: (i) Reference Standards Nos. 03/2023 and 01/2024, which set the methodology for indemnifying unamortized or depreciated investments; (ii) Reference Standard No. 05/2024, which introduces a risk matrix for public water supply and sanitation contracts; (iii) Reference Standards Nos. 06/2024 and 13/2025, which regulate tariff models for water supply and sewage services; (iv) Reference Standard No. 09/2024, which sets operational indicators; (v) Reference Standard No. 11/2024, which standardizes water supply and sewage services across subnational regulatory entities; (vi) Reference Standard No. 13/2025, which establishes the tariff structure and social tariff for water supply and sewage services; and (vii) Reference Standard No. 15/2025, which sets forth guidelines for the progressive reduction of losses in water supply systems. Although ANA’s reference standards are not legally binding on subnational regulatory agencies, compliance is incentivized by their being a condition for access to federal financing and public funds. As a result, any delay in the issuance, adoption, or interpretation of such standards, or inconsistencies in their implementation by subnational regulators, may adversely affect the regulatory environment applicable to our operations. From a state regulatory perspective, the São Paulo State Public Services Regulatory Agency (ARSESP) is the authority responsible for regulating and overseeing public water supply and sewage services related to the Concession Agreement for URAE-1. ARSESP’s responsibilities include: (i) setting and adjusting applicable tariffs; (ii) establishing technical standards, recommendations, and procedures for service provision; (iii) defining criteria, indicators, formulas, quality standards, and performance parameters; and (iv) monitoring service performance and applying sanctions. ARSESP charges a regulatory oversight fee of 0.50% of the revenues directly derived from the services it regulates, net of applicable taxes. ARSESP Resolution No. 1,635/2025 established the regulatory agenda for 2025 and 2026, which includes: (i) updating the methodology for certification and validation of regulatory assets; (ii) updating the methodology for annual certification of investments in the sanitation sector; (iii) updating the definitions for charging customers with public network availability of water and sewage services who are not connected to the system; (iv) updating the quality indicator for pavement replacements in accordance with applicable municipal laws; (v) proposing alternative solutions adapted to local conditions, including informal and rural areas; and (vi) updating and standardizing the methodology for sharing efficiency gains (Factor X) for regulated gas pipeline and basic sanitation companies. Changes in ARSESP’s regulatory approach may affect certain aspects of our operations or require adjustments to our processes or investments. Although these regulatory activities are part of the ordinary course of the sector and we maintain ongoing engagement with the regulator, certain decisions may influence our operating costs, timelines, or expected returns under our concession agreements. From a local regulatory perspective, municipalities are responsible for addressing matters of local interest, such as zoning within their territories and any conditions that may apply to our operations. In municipalities where services are provided outside a regionalized framework — such as in Olímpia — the municipality is responsible for delegating regulatory and oversight authority to a designated entity or exercising such powers directly through its own administrative body. Under the Concession Agreement for URAE-1, we are entitled to seek the restoration of the economic and financial equilibrium of the concession for impacts arising from the creation, repeal, or revision of rules issued by ANA, the granting authority, ARSESP, the State, or the municipalities, to the extent such rules affect our concession activities. The restoration of such equilibrium must preferably be addressed through periodic tariff reviews; however, regulatory changes that materially affect our solvency or liquidity may be addressed through extraordinary tariff reviews. For more information, see “Item 3.D. Risk Factors—We are exposed to risks associated with the Concession Agreement for URAE-1, which may materially impact our financial condition and operating results.” 55 Table of Contents Agreements with Municipalities and Metropolitan Regions In metropolitan regions, conurbations and microregions, the authority for public water and sewage systems is shared between states and municipalities. For other municipalities, the primary responsibility rests with the municipality itself. ARSESP ARSESP regulates, controls and supervises piped gas and basic sanitation services in São Paulo. It oversees state-owned services and those delegated to the state, including tariff regulation, while respecting municipal competencies. ARSESP charges a fee of 0.50% of the revenue directly obtained with the service provision it regulates, less taxes levied on it. ARSESP has addressed the methodology and criteria for updating the Regulatory Remuneration Base (Base de Remuneração Regulatória), along with the procedures for the Annual Certification of Investments for companies in the basic sanitation sector. Topics covered include asset control for basic sanitation concessionaires, general conditions for the provision and use of public urban cleaning and solid waste management services, and the risk allocation matrix associated with the provision of water supply and sewage services. Following our Privatization, ARSESP Resolution No. 1635/2025 established the regulatory agenda for 2025 and 2026, which includes: • Updating the methodology for certification and validation of regulatory assets; • Updating the methodology for annual certification of investments in the Sanitation sector; • Updating the definitions for charging clients with public network availability of water and sewage services who are not connected to the system; • Updating the quality indicator of pavement replacements according to municipal laws; • Proposing alternative solutions adapted to the local reality, individual or collective, including informal and rural areas; and • Updating and standardizing the methodology of the sharing of efficiency gains (Factor X) for regulated gas pipeline and basic sanitation companies. Marketing Channels As of December 31, 2025, we were the concessionaire responsible for providing water supply and sewage collection, treatment, and disposal services directly to end consumers in 375 municipalities in the State of São Paulo. For more information on our marketing channels targeted at individual customers, see “Item 4.B Business Overview—Customer Relationship.” We also supplied water and sewage services on a wholesale basis to two municipalities in the São Paulo metropolitan region. These municipalities are responsible for distributing the water to end consumers. Due to the structure of our distribution network, end consumers in areas served on a wholesale basis cannot obtain water services directly from us. For more information regarding our service concessions, see “Item 4.B Business Overview—Water Operations.” For more information on our marketing channels aimed at municipalities, see “Item 4.B Business Overview—Competition — Competition for New Municipalities.” Power Consumption Power is essential to our operations and, as a result, we are one of the largest users of energy in the State of São Paulo. In the year ended December 31, 2025, we used 3.259 GWh. Any significant disruption of energy supply could have a material adverse effect on our business, financial condition, results of operations, or prospects. Energy prices have a significant impact on our results of operations. For the year ended December 31, 2025, we purchased approximately 76.0% of our total energy consumption in the independent energy contracting market (Ambiente de Contratação Livre or Mercado Livre de Energia, or “ACL”) where we can more efficiently negotiate the supply of energy because we can take advantage of market opportunities; and the remainder of our energy consumption comes from the regulated energy contracting market (Ambiente de Contratação Regulado or Mercado Cativo, or “ACR”), where energy is priced through tariffs set by the National Electric Energy Agency (Agência Nacional de Energia Elétrica, or “ANEEL”). 56 Table of Contents In 2019, we began structuring a distributed power generation program (Programa de Geração Distribuída - Energia Fotovoltaica) focused on solar energy. The program estimates that until the end of 2027, we will have a power generation capacity of around 60 MW, with a daily average output of 28 MWh, corresponding to about 4% of our total energy consumption (based on energy consumed during 2025). By 2025, we had installed 36 photovoltaic power generation plants, with a power generation capacity of 50 MW. The credits obtained as part of this distributed generation were used to offset energy consumption of low voltage installations, which have a higher tariff. As such, about 55% of our low-voltage energy consumption is supplied by renewable energy. The total investment contemplated by this program is approximately R$320.0 million, with an estimated payback period of seven to eight years. Insurance We maintain insurance covering, among other things, fire or other damage to our property and office buildings and third-party liabilities. We also maintain insurance coverage for directors’ and officers’ liability (“D&O Insurance”). We currently obtain our insurance policies via Requests for Proposals (“RFPs”) involving major global insurance companies that operate in Brazil. For the year ended December 31, 2025, we paid R$162.2 million in premiums, of which R$9.4 million related to our D&O Insurance policy. Our insurance policies covered R$126.6 billion in assets and third-party liabilities, including coverage of R$210.0 million under our D&O Insurance policy, as well as Engineering Risk Insurance, Operational Risk Insurance, Environmental Risk Insurance, and General Liability Insurance. We do not have insurance coverage for business interruption risk because we believe that the low risk of significant interruption to our activities does not justify the high premiums for such insurance. We believe that we maintain customary insurance levels for our type of business in Brazil. For further information, see “Item 3.D. Risk Factors — Risks Relating to the Regulatory Environment — Risks associated with the collection, treatment and disposal of wastewater and the operation of water utilities may impose significant costs that may not be covered by insurance, which could result in increased insurance premiums.” Intellectual Property Trademarks and copyrights We have secured registration of our trademark (“Sabesp”) in its nominative form in Class 37 (i.e., energy, water, gas and sewage distribution and control services) at the Brazilian Institute of Industrial Property (Instituto Nacional da Propriedade Industrial - “INPI”). In addition, we have registered other trademarks with the INPI. We have also registered figurative trademarks for twelve characters and have secured copyright registration for the character “Sani” with the School of Fine Arts of the Federal University of Rio de Janeiro (Escola de Belas Artes da Universidade Federal do Rio de Janeiro - UFRJ). Of the trademark applications we have filed with the INPI, only one remains pending final decision and registration. Patents We have seven patents granted by the INPI: (i) a device for the removal of supernatants during the sewage treatment process, (ii) a rotary device used to clean water reservoirs transported by trucks with high-pressure hydro-jetting systems, (iii) a bubble removal system, autonomous micro-laboratory, and use of an autonomous micro-laboratory to monitor water quality, together with USP, (iv) a chemical composition sensor, its fabrication process and its use to measure pH in microfluid systems, together with USP, (v) water leakage detection equipment: method and simulation bench for leakage in lines, together with FAPESP and UNESP, (vi) a device for the installation of water meters; and (vii) a modular system for the treatment of sanitary sludge and the process using this system. 57 Table of Contents We have filed patent applications for additional devices and inventions, some of which have been jointly filed with certain Brazilian universities pursuant to our cooperation agreements with these institutions. We currently have nine patent applications pending before the INPI. In addition to these Brazilian patent applications, we also filed two international patent applications under the Patent Cooperation Treaty (“PCT”), designating the European Patent Office. In 2025, we obtained a European patent entitled “Method and System for Analyzing and Providing a Quality Index for a Noise Correlator” for water leakage detection equipment, filed jointly with FAPESP and UNESP. We currently have one patent application pending under the PCT system. For more information on our cooperation agreements with Brazilian universities and FAPESP, see “Item 5. Operating and Financial Review and Prospects —C. Research and Development, Patents and Licenses, etc. —Research and innovation.” Software We have adopted an internal policy that provides for an active and effective audit and prevention of unauthorized software use. We have acquired temporary the software licenses for the use of third-party software, through contracts and/or other legally valid instruments, which are required for all of our workstations. We have also developed 28 computer programs for management and control of water and sewage treatment facilities, as well as for third-party services management for the management and control of the water treatment process and Electric energy management system. We have also registered the proprietary computer programs at the INPI. Domain Names We own the domain names listed below, which have been registered with the relevant entity in Brazil, Registro.br: • www.sabesp.com.br; • www.revistadae.com.br; • Sabesp2via.net; and • www.clubinhosabesp.com.br. Environmental Matters Given the multidisciplinary nature of sanitation services, in addition to developing a corporate climate strategy, we undertake several initiatives aimed at preserving the environment. Our current corporate strategy places sustainability at the core of our business, and our environmental initiatives have gained momentum, reflecting our commitment to proactively addressing the most pressing environmental and climate challenges. Environmental management is integral to the provision of our services and to our core business strategy. Our performance is guided by established environmental standards and monitored through an integrated approach to ensure the sustainability of our operations. With the recent organizational restructuring, the environmental licensing process for works and projects, which was previously decentralized among our various business areas, has been centralized in a single department, enabling a comprehensive overview covering all phases of the process, from conception to decommissioning of facilities. The management of compliance with the conditions of our environmental licenses has also been incorporated into this centralized function. 58 Table of Contents This centralized management brings several benefits. By concentrating on the licensing process within a single area, we have enhanced the efficiency of our management, standardized and simplified procedures, and optimized internal communication. This also provides a more comprehensive and integrated perspective on our activities, enabling a more strategic and consistent approach to environmental issues. By incorporating the management of compliance with environmental license conditions into this function, we further reinforce our commitment to legal compliance and sustainability. We have the following ongoing environmental programs, managed by our Environmental, Regulatory and Sustainability corporate areas: • Management of GHG emissions, including: conducting annual GHG inventories; promoting awareness-raising activities on climate issues; encouraging and supporting the reduction of GHG emissions in our operations; conducting studies to identify the potential for carbon sequestration and storage in our forest reserves; performing climate change risk and resilience assessments; and adhering to relevant national and international initiatives and guidelines. In 2023, 2024 and 2025, we were awarded the GHG Inventory Gold Seal by the Brazilian GHG Protocol Program. For more information, see “Item 4.B. Business Overview — Environmental Matters — Climate Change Regulations: Reduction of Greenhouse Gases (GHG) Emissions;” • Corporate program for obtaining and maintaining licenses for water treatment plants, sewage treatment plants, and sewage pumping stations (Programa Corporativo de Obtenção e Manutenção de Licenças de Estações de Tratamento de Água, Estações de Tratamento de Esgotos e Estações Elevatórias de Esgotos), designed to meet the requirements of the licensing authority and to establish procedures for the renewal and ongoing maintenance of these licenses. We have had a program since 2017, approved by CETESB, relating to the operational licenses of sewage pumping stations. In 2022, a similar program was approved by CETESB for water treatment plants and wastewater treatment plants; • Corporate program for obtaining and maintaining grants for the use of water resources (Programa Corporativo de Obtenção e Manutenção das Outorgas de Uso de Recursos Hídricos), including water collection, effluent discharge and dams operations. The grant provides the necessary resources to subsidize the processing of use of and payment for water resources. We are the biggest payer for water use in the State of São Paulo; • Environmental education program (Programa de Educação Ambiental - “PEA”), an important tool for strengthening the effectiveness of our sanitation activities, which propitiates connections with the communities we service through over several environmental education projects. The activities developed by the PEA are organized with the following objectives: raise awareness of the intrinsic value of water; protect the environment; preserve water bodies; improve the quality of the environment; raise awareness of sanitation activities; and raise awareness of the conscious use of water; • Management of our institutional representation in the state and national systems of water resources, including training of company representatives to participate in: (i) the creation of criteria for water usage charges, (ii) preparation and review of river basin plans (Planos de Bacias), (iii) review of water bodies’ classifications, and (iv) analysis of legislations regarding the protection of water sources; • SABESP 3Rs program (Programa SABESP 3Rs) for the reduction, reuse and recycling of waste from administrative activities, in partnership with waste and recycling collecting cooperatives and which includes employee training enabling them to act as multipliers in the roll-out of the program; • Progressive implementation and maintenance of the Environmental Management System (“EMS”) in our water and sewage treatment plants aiming to improve the efficiency of the systems, manage the risks and implement preventive actions to avoid impacts on the environment, considering the relevance of these plants for our core activity. Since 2015, we have been working on the EMS with a mixed model, whereby the ISO 14001 standard is applied to a limited number of certified plants, while the other plants adopt the environmental management model developed internally (named SGA-SABESP), without aiming certification. The EMS is currently in place in 834 treatment plants, 35 of which are ISO 14001 certified, representing 100% of our treatment plants. 59 Table of Contents • Corporate program of environmental recovery commitment terms (Programa Corporativo de Termos de Compromisso de Recuperação Ambiental) arising from the environmental licensing of new ventures, which includes obligations of forest restoration with environmental compensation purposes, when necessary. From 2017 to 2025, we accounted for 2,758 thousand buds for plantation. Of these, 1,536 thousand have already been planted. To provide technical support for environmental programs, we carry out corporate training on topics related to environmental management. This initiative aims to promote continuous professional development with specific content aimed at strategic, management and operational teams. In addition to corporate environmental management actions, we have several projects and initiatives underway to benefit the environment, such as actions to protect water springs, projects for the rational use of water, reuse of effluents, projects for the use of photovoltaic energy and biogas as vehicle fuels, as well as other environmental projects focused on the engagement of the population at large. We are a signatory of the United Nations Global Compact, support the 17 United Nations Sustainable Development Goals and maintain a partnership with the United Nations Framework Convention on Climate Change (UNFCCC). These initiatives aim to stimulate actions in areas of crucial importance to humanity, the planet, countries and companies, including the enhancement of sanitation services for the preservation of the environment, quality of life and the mitigation of climate change. Climate Change Regulations: Reduction of Greenhouse Gases (GHG) Emissions We are required to comply with laws and regulations related to climate change, including international agreements and treaties to which Brazil is signatory. At the state level, we are also subject to the State Policy on Climate Change for the State of São Paulo (Law No. 13,798/2009), regulated by Decree No. 68,308/2024. At the federal level, we are subject to the National Climate Change Policy (Law No. 12,187/2009), regulated by Decree No. 9,578/2018. Also at the federal level, in 2024 the Brazilian Greenhouse Gas Emissions Trading System (SBCE) was created by Law No. 15,042/24, which has not yet been regulated. In 2025, we concluded our annual GHG inventory, revealing that sewage collection and treatment activities are our main source of GHG emissions, accounting for 76.7% of our total annual GHG emissions in the year ended December 31, 2025. Electricity accounted for 6.04% of our total annual GHG emissions in the year ended December 31, 2025. As we expand our services, we expect increased organic loads and GHG emissions but also contribute to reducing GHG emissions in aquatic ecosystems, aligning with the Climate Action Plan 2050. We are exploring less carbon-intensive alternatives in our operational activities and with the support of a specialized consultancy, both in the context of adaptation and climate mitigation. We have already evaluated plans for a series of actions aimed at reducing GHG emissions, including: • the use of complementary technologies and the optimization of the operations in sewage treatment plants; • the expansion of the beneficial use of biogas and generated sludge; • the expansion of the use of clean and renewable energy sources and alternative fuels; and • activities of forest conservation and restoration. Among the actions already implemented or currently in progress, we highlight the following examples, as detailed in the paragraphs below. Additionally, we are developing projects aimed at generating clean, renewable, and sustainable energy. In 2019, we began structuring a distributed power generation program (Programa de Geração Distribuída - Energia Fotovoltaica) focused on solar energy. The program estimates that until the end of 2027, we will have a power generation capacity of around 60 MW, with a daily average output of 28 MWh, corresponding to about 4% of our total energy consumption (based on energy consumed during 2025). By 2025, we had installed 36 photovoltaic power generation plants, with a power generation capacity of 50 MW. The energy credits obtained as part of this distributed generation were used to offset energy consumption of low voltage installations, which have a higher tariff. As such, about 55% of our low-voltage energy consumption is supplied by renewable energy. The total investment contemplated by this program is approximately R$320.0 million, with an estimated payback period of seven to eight years. 60 Table of Contents We produce agricultural compost, “Sabesfértil”, from sludge at a wastewater treatment plant in the municipality of Botucatu. Similar projects for the use of sludge from wastewater treatment plants are under development at our other plants. In the coastal region, we have developed a system for the solar drying of wastewater treatment plant sludge with forced ventilation and mechanized mixing and fragmentation of the sludge. A similar project is already in operation in a wastewater treatment plant located in the central-west region of the state. In the Franca wastewater treatment plant, we use biogas to produce vehicle fuel to supply part of our fleet, reducing GHG emissions. We also have projects to cover sewage treatment anaerobic lagoons to capture and burn the biogas. We are developing methane reduction projects and energy recovery initiatives at wastewater treatment plants, along with research into small hydro-generators. We have also implemented projects for the covering of anaerobic lagoons with the covering supported in the liquid surface. We are implementing sustainability initiatives in our corporate vehicle fleet. This significantly reduced annual gasoline consumption, avoiding GHG emissions. We engage in discretionary forest reserve maintenance and restoration activities, contributing carbon sequestration and climate adaptation. We preserve more than 36,000 hectares of rain forest (Mata Atlântica) within legally protected areas (Brazilian conservation units), where the main metropolitan springs and water reservoirs are located. Water Usage The use of water resources in Brazil is regulated by Federal Law No. 9,433/1997, which establishes the National Water Resources Policy. This law requires prior authorization for any use of water resources that may impact the natural system, quantity, or quality of water in a given body of water. As a result, our water use-including water supply and effluent discharge-requires a water grant (outorga de uso da água) or, in specific cases, a formal waiver, provided that all legal requirements are met. The authority responsible for issuing the water grant depends on the domain of the water body, for example, whether it is under federal or state domain. If the water body falls under federal domain, ANA is responsible, and the legal requirements are outlined in Federal Law No. 9,433/1997 and ANA’s Resolution No. 1,941/2017. For water bodies under the domain of the State of São Paulo, SP Águas is the public authority which grants the authorization, and the legal requirements are outlined in the State Water Policy, Law No. 7,663/1991, and in the State Supplementary Law (Lei Complementar) No. 14,013/2025, as well as DAEE’s Ordinance No. 1,630/2017. Noncompliance with the applicable law regarding the use of water resources may result in environmental liabilities, such as administrative infraction and environmental crime, without prejudice to the obligation to indemnify eventual damage caused to the environment. At the administrative federal level, sanctions can range from simple warning, the application of fines ranging from R$50.00 to R$50.0 million and the prohibition of the source of use of water resources, which may indirectly impact related developed activities. This amount can be doubled in the event of a repeat offense. In addition, water pollution may subject the offender to fines ranging from R$50.00 to R$50.0 million. State law establishes the basic principles governing the use of water resources in the State of São Paulo in accordance with the State constitution. These principles include: • rational utilization of water resources, ensuring that their primary use is to supply water to the population; • optimizing the economic and social benefits resulting from the use of water resources; 61 Table of Contents • protection of water resources against actions which could compromise current and future use; • defense against critical hydrological events which could cause risks to the health and safety of the population or economic and social losses; • development of hydro-transportation for economic benefit; • development of permanent programs of conservation and protection of underground water against pollution and excessive exploitation; and • prevention of soil erosion in urban and rural areas, with a view to protecting against physical pollution and silting of water resources. State Law No. 12,183/2005 established the basis for charging for the use of the water resources under the domain of the State of São Paulo. The criteria for calculating the amount of the charge are proposed by the river basin committees and must be submitted for approval to the state water resources council and formalized by a specific decree issued by the Governor of the State of São Paulo. In accordance with current legislation, the river basin committees prepare and approve rules and criteria for the implementation of the charges, and the National Water Agency, SP Águas and the Basin Agencies (Agências da Bacia) are authorized to charge users, such as us, for the water collection or discharge of effluents into water bodies. The State of São Paulo has a total of 21 river basin committees, four of which operate in basins that extend across more than one state, classified as interstate. Charging for the use of water resources has already been implemented by all river basin state committees since 2024. For the year ended December 31, 2025, we paid approximately R$98.1 million for the collection and discharge into federal and state-controlled rivers. Water Quality Annex XX of Consolidation Ordinance No. 5, amended by Ordinance No. 888 of May 2021, issued by the Ministry of Health of the federal government, provides the standards for potable water for human consumption and establishes potability standards in Brazil. It also outlines rules for sampling and limits related to substances that are potentially hazardous to human health. In compliance with Brazilian law, the physical-chemical, organic and bacteriological analyses carried out for water quality control must follow national and international standards, such as: Standard Methods for the Examination of Water and Wastewater, amongst others. Federal Decree No. 5,440/2005 determines the disclosure of water quality information to consumers. We have been complying with this regulation by publishing the required information on monthly bills and annual reports delivered to all consumers that we serve. Environmental Regulation The development, implementation and operation of water and sewage systems are subject to federal, state and local laws and regulations on environmental and water-resource protection. CONAMA and IBAMA are the primary federal agencies overseeing activities with potential environmental impacts. At state level, CETESB is responsible for controlling, supervising, monitoring and licensing of polluting activities. Environmental control and planning in Brazil are governed by a combination of federal and state laws and regulations. These legal instruments establish guidelines for pollution control, water resource management, and environmental licensing. 62 Table of Contents Federal Laws and Regulations We are subject to the following federal environmental laws and regulations in our operations, among others: • Supplementary Law No. 140/2011: Regulates: (i) environmental licenses, (ii) federal, state, and municipal jurisdiction over environmental matters, (iii) activities subject to licensing, and (iv) environmental impact studies and reports. • Brazilian Forestry Code (Law No. 12,651/2012): Requires the preservation of permanent protection areas (APPs), particularly around water springs and reservoirs. Recognizes these areas as essential for: (i) water security, (ii) geological stability, (iii) biodiversity conservation, and (iv) soil nutrition. • CONAMA Resolution No. 05/1988: Requires environmental licensing for sanitation projects that significantly alter the environment. • CONAMA Resolution No. 357/2005, amended by Resolution No. 430/2011: Establishes standards for the discharge of effluents into water bodies. • ANA Resolution No. 236/2024: Establishes updated rules for the use of federal water resources, including the procedures for regularization, revision, and suspension of water-use rights. Defines risk levels for economic activities, identifies insignificant uses and non-outorga interventions, and sets users’ obligations. • Federal Law No. 15,190/2025 — General Environmental Licensing Law: Establishes nationwide rules for environmental licensing, standardizing procedures across federal, state, and municipal levels. Maintains the traditional three-stage licensing structure (preliminary, installation, and operation licenses) and introduces additional licensing modalities — the Environmental Single License (LAU), the License by Adhesion and Commitment (LAC), and the Special Environmental License (LAE) — allowing procedures to be adapted according to the scale, impact, and risk of each activity, while maintaining environmental protection standards. • Federal Law No. 9,605/1998 — Environmental Crimes Law: Defines administrative, civil, and criminal sanctions for conduct harmful to the environment, establishing liability for individuals and legal entities and enabling penalties such as fines, restrictions of rights, and suspension of activities. State Laws and Regulations (São Paulo): We are subject to the following state environmental laws and regulations in our operations, among others: • State Law No. 997/1976, regulated by Decree No. 8,468/1976 and its amendments: (i) establishes environmental pollution control mechanisms and (ii) defines standards for effluent discharge at the state level. • State Law No. 9,509/1997, regulated by State Decree No. 47,400/2002: Defines São Paulo’s state environmental policy. • DAEE (São Paulo State Department of Water and Electricity) Ordinance No. 1,630/2017: Governs the concession of water-use rights and interventions in water resources at the state level. • CETESB Board Decision No. 03/2014/P, as amended: establishes procedures and criteria for environmental licensing in the State of São Paulo, including licensing modalities (Preliminary License – LP, Installation License – LI, and Operating License – LO) and guidelines for the filing and review of administrative proceedings; • CETESB Board Decision No. 217/2014/I/C: sets forth criteria for the classification of projects and activities subject to environmental licensing, including classification based on pollution potential and scale; and 63 Table of Contents • CETESB Board Decision No. 038/2017/C: consolidates administrative procedures applicable to environmental licensing, including guidelines for technical review and the processing of administrative proceedings. Our reservoirs that were operational before the enactment of the laws and regulations described above are exempt from developing a PACUERA (Environmental Plan for the Conservation and Use of the Surroundings of the Reservoir), as such obligation applies only to reservoirs established thereafter. Environmental Licensing Environmental licensing in Brazil is governed by federal, state, and local laws, requiring a license for activities that (i) use natural resources, (ii) are effectively or potentially polluting, or (iii) can cause environmental damage. Federal Law No. 6,938/1981 (National Environmental Policy) mandates prior licensing, while Supplementary Law No. 140/2011 divides licensing responsibilities among IBAMA, state, and municipal authorities. Federal Law No. 15,190/2025 (General Environmental Licensing Law) now establishes nationwide rules for environmental licensing, standardizing procedures and introducing new licensing modalities and criteria across all government levels. • IBAMA: Licenses activities across multiple states, in federal areas, or involving nuclear energy. • Municipal authorities: License activities with strictly local impact. • State environmental agencies: Handle all other licensing. The enactment of Law No. 15,190/2025 (Brazilian General Environmental Licensing Law – “LGLA”) has significantly restructured the environmental licensing framework in Brazil. While maintaining the traditional three-stage licensing model (preliminary, installation and operation licenses) as a reference, the LGLA introduced new licensing modalities, including the Single Environmental License (Licença Ambiental Única – “LAU”), the License by Adhesion and Commitment (Licença por Adesão e Compromisso – “LAC”), the Special Environmental License (Licença Ambiental Especial – “LAE”), and the Corrective Operating License (Licença de Operação Corretiva – “LOC”), aimed at simplifying procedures and tailoring licensing requirements to the nature, scale and risk level of each project. The LGLA applies to all entities within the Brazilian National Environmental System (Sistema Nacional do Meio Ambiente – “Sisnama”), in accordance with the allocation of competencies established under Law No. 140/2011. Notwithstanding its entry into force, certain provisions of the LGLA—particularly those related to exemptions from environmental licensing— are currently subject to constitutional review before the Brazilian Supreme Federal Court (Supremo Tribunal Federal – “STF”), in the context of Direct Actions of Unconstitutionality (Ações Diretas de Inconstitucionalidade – “ADIs”) Nos. 7,913, 7,916 and 7,919, and their application may be subject to adjustments or interpretative limitations. For the sanitation sector, the LGLA establishes a differentiated regulatory framework, including procedural simplification and priority in the analysis of water supply and wastewater treatment projects. Pursuant to Article 10, §2, such systems and facilities are, as a rule, exempt from environmental licensing until the universalization targets set forth in Federal Law No. 11,445/2007 are achieved, without prejudice to the requirement to obtain water use rights for effluent discharge. Projects with significant environmental impact require an Environmental Impact Assessment and Environmental Impact Report (Estudo de Impacto Ambiental — “EIA” and Relatório de Impacto Ambiental — “RIMA”), with a minimum 0.5% environmental offset. The licensing process typically consists of three stages: preliminary license, installation license, and operation license. Environmental licenses must be periodically renewed, with renewal requests filed up to 120 days prior to the expiration date. Non-compliance with license conditions may lead to administrative sanctions, including fines or license revocation. Operating without a valid environmental license constitutes an administrative infraction and environmental crime, subject to fines of up to R$50.0 million and joint and several liability for environmental damage, regardless of fault or intent. 64 Table of Contents In the State of São Paulo, CETESB oversees licenses and pollution control. CETESB Executive Officers’ Resolution No. 012/2022/C launched a licensing regularization program for water treatment plants and sewage treatment plants, to be completed by 2027. We have implemented corporate programs for obtaining and maintaining licenses, covering water treatment plants and sewage pumping stations, as well as for environmental recovery commitment terms, including forest restoration and environmental compensation, aligned with CETESB Resolution No. 012/2022/C. Sewage Requirements In the State of São Paulo, effluent must meet applicable requirements before discharge into the public sewage system. Effluent treated at our sewage treatment facilities must comply with: (i) effluent limitation guidelines and (ii) water quality standards applicable to the receiving water bodies, as established by federal and state legislation. CETESB is authorized to: (i) monitor effluent discharges into water bodies and (ii) issue environmental licenses to polluting sources, including sewage treatment plants. Both state and federal water resource legislation establish fees for the discharge of treated effluents into water bodies, which are already in effect in most river basins. Environmentally Protected Areas We manage and protect approximately 49,000 hectares within conservation units, as defined by Federal Law No. 9,985/2000. The Cantareira System management plan for its Environmental Protection Area (Área de Proteção Ambiental — “APA”) was formally approved by Decree No. 65,244/2020. This structured approach ensures the preservation and sustainable management of critical water resources in compliance with federal and state environmental legislation. Environmental Liabilities Environmental liability in Brazil is comprehensive and strict, applying to individuals and legal entities that cause direct or indirect environmental damage through action or omission. It is regulated under civil, administrative, and criminal law, ensuring that environmental harm is remediated, sanctioned, and prevented. Pursuant to Federal Law No. 6,938/1981 (National Environmental Policy), Brazil adopts a strict liability standard for civil environmental liability, meaning (i) liability is applied regardless of fault or intent, and (ii) evidence of a causal link between the damage and an enterprise or activity is sufficient to trigger the obligation to remediate the environmental harm. Environmental civil liability is joint and several, meaning all parties — individuals and legal entities — directly or indirectly involved in the activity that caused environmental damage can be held fully liable. If multiple parties are responsible, the financially strongest party may be required to bear the full remediation cost but may later seek recourse against other responsible parties through: (i) contractual agreements or (ii) judicial action demonstrating the involvement of others. Courts may pierce the corporate veil when a party obstructs environmental remediation, even without proof of fraud or misuse of the corporate structure. The mere failure to remediate environmental damage is sufficient to justify holding shareholders personally liable in the civil sphere. There is no cap on the amount courts may award for: (i) repairing environmental damage or (ii) compensation if the damage is deemed irreparable. A recent precedent from the Brazilian Federal Supreme Court ("STF") abolished the statute of limitations for lawsuits seeking reparation or compensation for environmental damage. Under Federal Decree No. 6,514/2008, any action or omission that violates applicable environmental regulations constitutes an environmental administrative infraction, even if no actual environmental damage has occurred. Administrative sanctions and penalties vary based on the severity of the infraction and the economic capacity of the offender. Sanctions may include: (i) fines (single or daily), (ii) warnings, (iii) restriction of rights, (iv) seizure of products and byproducts, (v) closure of facilities, (vi) prohibition from contracting with public entities, (vii) suspension of permits, (viii) loss of financial or fiscal benefits, and (ix) full or partial suspension of activities. 65 Table of Contents Legal entities can be held criminally liable for environmental offenses under Federal Law No. 9,605/1998. If convicted, penalties may include: (i) fines, (ii) temporary bans on rights, (iii) partial or total suspension of activities, and (iv) other sanctions, independent of any administrative penalties or civil liabilities related to the same facts. The criminal liability of legal entities does not exclude the criminal liability of natural persons (e.g., officers, board members, or technical staff) who authorized, participated in, or facilitated the offense. Scope of Business In connection with the scope of our services, State Supplementary Law No. 1,025/2007 amended State Law No. 119/1973 and expanded the range of services that we may provide, including urban rainwater drainage and management, urban cleaning and solid waste management, as well as power generation, storage, conservation, and sales activities, for our own or third-party use. C. Organizational Structure Not applicable. D. Property, Plant and Equipment Our principal property, plant and equipment comprise administrative facilities which are stated at historical costs less depreciation. The reservoirs, water treatment facilities, water distribution networks consisting of water pipes, water transmission lines, water connections and water meters, sewage treatment facilities, and sewage collection networks consisting of sewer lines and sewage connections are recorded as contract assets and intangible assets (concession assets). As of the date of this annual report, we operate 214 water treatment facilities, 690 simplified water treatment facilities and 641 sewage treatment facilities, including eight ocean outfalls, as well as 18 water quality control laboratories. As of December 31, 2025, the total net book value of our property, plant and equipment, intangible assets and contract assets and other concession assets was R$62,401.8 million. All of our material properties are located in the State of São Paulo.