Cal. Water Code § 74593

A district, whenever the board deems it to be to the advantage of the district so to do, may: (a) Enter into contracts with municipalities, sanitary districts or other incorporated bodies, either within or without the district, providing for the delivery to the district of sewage or storm water produced by or coming from such municipalities, sanitary districts, or other incorporated bodies. (b) Treat, purify, and recycle such water for beneficial use. (c) Store, distribute, sell, or otherwise dispose of the water and byproducts resulting from such treatment, purification, or recycling. The district may construct and operate the works necessary for such purposes, and may acquire or construct and may maintain pipelines, flumes, ditches, and reservoirs suitable or adaptable for the prevention of the wastage of water. Whenever the district receives a revenue from the sale of water and byproducts in excess of the cost of operating and maintaining the works authorized in this section, it may, for the purpose of enlarging, extending, or improving such works, issue its certificates of indebtedness payable out of such excess revenues, and pledge the same for the payment of the indebtedness so created.