California Code, Water Code - WAT § 55335

A district may acquire and conserve water supplies from any available source, including underground water basins within the same county, imported supplies, streams, waste water and storm water.

A district may acquire, purify, treat and reclaim saline water or sewage or both;  may store, distribute, and sell the water and by-products resulting from such purification, treatment and reclamation;  and may acquire, construct and maintain pipelines, flumes, ditches, reservoirs, sewage purification plants, sewage collection systems, saline water demineralization plants, and such other works and facilities as are necessary or convenient to carry out these powers.