- a)Directing and overseeing everything concerning the provision of a drinking water service for the inhabitants of the republic, the collection and disposal of wastewater and liquid industrial waste, and stormwater in urban areas; b) Determining the priority, suitability, and feasibility of the different projects proposed to construct, renovate, expand, or modify aqueduct and sewer works; which may not be executed without its approval; c) Promoting the conservation of hydrographic basins and ecological protection, as well as the control of water pollution; d) Advising other State bodies and coordinating public and private activities in all matters relating to the establishment of aqueducts and sewers and the control of water resource pollution, its consultation being mandatory in all cases, and compliance with its recommendations being inexcusable; e) Preparing all plans for public works related to the purposes of this law, as well as approving all those for private works related to aqueduct and sewer systems, as determined by the respective regulations; f) Utilizing, using, governing, or supervising, as the case may be, all public domain waters essential for the due fulfillment of the provisions of this law, in exercise of the rights that the State holds over them, in accordance with Law No. 276 of August 27, 1942, to which effect the Institute shall be considered the substitute body for the powers attributed in that law to the State, ministries, and municipalities; g) Directly managing and operating the aqueduct and sewer systems throughout the country, which shall be assumed gradually, taking into account convenience and resource availability. The systems currently managed and operated by municipal corporations may remain in their charge, as long as they provide an efficient service. Under no circumstances may it delegate the administration of the Metropolitan Area's aqueduct and sanitary sewer systems.
Nor may it delegate the administration of systems for which there is financial liability and while this liability corresponds directly to the Institute.
The institution is empowered to agree, with local bodies, on the administration of such services or to administer them through administrative boards of mixed composition between the Institute and the respective communities, whenever this is suitable for the better provision of services and in accordance with the respective regulations.
For the same reasons and with the same characteristics, regional administrative boards involving several municipalities may also be created.
In the case of local bodies that are constituted as Community Aqueduct Administrative Associations (Asociaciones Administradoras de Acueductos Comunales, Asadas), under the terms of Law 218, Law of Associations, of August 8, 1939, and Law 8901, Law on the Minimum Percentage of Women that Must Integrate the Boards of Associations, Unions, and Solidarity Associations, of November 18, 2010, the Asadas must guarantee the right of voluntary association by respecting equal representation on the Board of Directors in accordance with the law, except in cases where, due to poverty or lack of interest, such equal representation cannot be fulfilled. All members shall have the right to participate in assemblies, to run for office, and to represent the association in the corresponding bodies. Likewise, they must ensure compliance with Law 6968, Convention on the Elimination of All Forms of Discrimination Against Women, of October 2, 1984, and Law 7142, Law on the Promotion of Women's Social Equality, of March 8, 1990.
Members shall be understood to mean natural or legal persons, represented by their legal representative, nationals or foreigners with permanent residence, who are users with service in their name, in their capacity as owners or members of the family unit, demonstrated through a sworn declaration, usufructuaries, concessionaires, or legitimate possessors of the property where the drinking water supply and wastewater sanitation service is located, who also complete their affiliation process. Natural persons may exercise the right of association voluntarily up to a maximum of two persons per property, provided that at least one of the persons is a woman. Only one person per property may simultaneously hold a position on the Board of Directors. In the event that a person owns two or more properties, they may only represent one of all the properties.
In the same manner, the Asadas shall gradually promote the voluntary participation, affiliation, and representation of young people over 18 years of age and under 35 years of age, users of the services mentioned, based on their real availability and without affecting the freedom of association or the operability of the Asada, in accordance with Law 8261, General Law of the Young Person, of May 2, 2002.
(Subsection g) above thus amended by the sole article of the Law to Guarantee Gender Parity and Promote Youth Participation in the Administrative Associations of Community Aqueducts and Sewers, No. 10873 of March 16, 2026) h) Enforcing the General Drinking Water Law, for which purpose the Institute shall be considered the substitute body for the ministries and municipalities indicated in said law; i) Building, expanding, and renovating aqueduct and sewer systems in those cases where necessary and as advisable for the best satisfaction of national needs; and j) Controlling the proper investment of all resources that the State allocates for aqueduct and sanitary sewer works.
(*)k) The Costa Rican Institute of Aqueducts and Sewers is authorized to formalize, through an inter-institutional agreement with municipal corporations, the construction, expansion, and rehabilitation of works for the supply of drinking water and sewer service, with the purpose of providing these services in those areas where the Costa Rican Institute of Aqueducts and Sewers does not have coverage in certain areas, or where having coverage, it cannot provide the service due to constructive limitations of the system, but where the water resource is technically available.
The preliminary studies and the construction plans for the different drinking water and sewer systems carried out by the municipalities must have the prior approval of their technical and design aspects by the Costa Rican Institute of Aqueducts and Sewers, to ensure their incorporation into the systems already operated by the Institute, once the works are completed, in accordance with subsection b).
Municipalities are authorized to prepare, by themselves or through third parties, the construction plans for the aqueduct and sewer systems.
Once the work constructed by the municipal corporation is received satisfactorily by the Costa Rican Institute of Aqueducts and Sewers, the corresponding item must be incorporated into the service rate to make the full payment in favor of the municipal corporation, for the work previously approved by the AyA, as well as the cost of expropriations and constitution of easements necessary for the construction and operation of the system. Both the work and the lands shall become part of the AyA's assets. The rate model for the payment of the work must be approved by the Public Services Regulatory Authority (Autoridad Reguladora de los Servicios Públicos, Aresep).
(*) (Subsection k) above thus added by article 1 of the Law to Permit Municipalities the Construction of Aqueduct and Sewer Works, No. 10595 of November 11, 2024) (Thus amended by article 1 of Law No. 5915 of July 12, 1976)