A study of water supply, water conservation, and wastewater reclamation and reuse in the San Francisco Bay Area was performed by the J. B. Gilbert & Associates division of Brown and Caldwell (14) for the Association of Bay Area Governments (ABAG). A municipal water-use projection model was developed to make use of detailed population, housing, employment, and land-use projections and to evaluate alternative water conservation strategies. The procedure and the results of the analysis of municipal water use and supply in the nine-county Bay Area are presented in this paper. The Bay Area used 934 mgd (3,540,000 m3/day) of water in 1975 for municipal purposes, including residential, commercial, and industrial uses. Of this amount, 54% was used by residential customers, 33% by commerce and industry, 7% by public authorities, and 6% was unaccounted for. Imported surface water accounted for approx. 53% of water delivered in the Bay Area. Ground water was the principal source of locally-derived water, providing 27% of the Bay Area’s needs. Local reservoirs provided the remainder of the supply. The water is distributed to Bay Area consumers by 83 separate agencies. The Bay Area population is expected to rise from 4,800,000 in 1975 to between 5,400,000 and 6,200,000 by the year 2000 (5). This growth will be accommodated primarily by the conversion of agricultural land to urban uses.