It is the purpose of this article, to permit certain public agencies to make the most efficient use of their powers relating to public water supplies and the transportation and treatment of wastewater by enabling them to cooperate with other public agencies on a basis of mutual advantage and thereby to provide services and facilities to participating public agencies and to provide for the establishment for such purpose of a quasi-governmental public corporation which shall be known as a regional water authority, or where appropriate, a regional wastewater authority, or regional water and wastewater authority. The function of the regional water authority shall be to secure a source of water on a scale larger than is feasible for individual public agencies acting alone, and to sell such water to public service districts, municipalities, publicly and privately owned water utilities, and others. The function of the regional wastewater authority shall be to enable public agencies to join together to provide the most economical method of transportation and treatment of wastewater and to provide such transportation and treatment services to public service districts, municipalities, publicly and privately owned wastewater utilities, and others. The function of the regional water and wastewater authority shall be to enable public agencies to join together to carry out the joint functions of both regional water authority and a regional wastewater authority.

In addition to the purposes for which it may have originally been created, any authority created pursuant to this article shall have the power to enter into agreements with public agencies, privately owned utilities, and other authorities, for the provision of related services including, but not limited to the following: Administration, operation and maintenance, billing and collection.