Domestic water use includes water for normal household purposes, such as drinking, food preparation, bathing, washing clothes and dishes, flushing toilets, and watering lawns and gardens. State agencies generally obtain reliable information from public suppliers about withdrawals and population served. Information on deliveries to various users was more difficult to obtain and generally was estimated from the population served.
The number of people served by their own water systems (self supplied) was determined by subtracting the number of people served by public suppliers from the total population as reported by the U.S. Bureau of the Census. The difference between these totals indicated that 42.8 million people, or 17 percent of the Nation's total population, were served by their own water-supply systems in 1990, compared with 42.5 million people in 1985. Self-supplied domestic systems rarely are metered and few data exist. Self-supplied domestic withdrawals were estimated using per-capita use coefficients that generally ranged from 50 to 120 gallons per person per day. Consumptive use estimates were based on coefficients, generally ranging from 10 to 50 percent of withdrawals and deliveries.
Domestic water use (withdrawals, deliveries) during 1990 was an estimated 25,300 Mgal/d (table 11: by water-resources region, table 12: by State), or 4 percent more than during 1985. Domestic use represents 7 percent of total freshwater use for all offstream categories. Domestic withdrawals were an estimated 3,390 Mgal/d. Ground water was the source for about 96 percent of domestic withdrawals; surface water was the source for the remaining 4 percent. More than 50 percent of the Nation's population is dependent on ground water for domestic use. Withdrawals for the population served by their own water systems averaged about 79 gal/d for each person, compared to 78 gal/d during 1985. Public suppliers delivered about 21,900 Mgal/d of water to domestic users; this accounted for 57 percent of total public-supply withdrawals. Public-supply domestic deliveries averaged 105 gal/d for each person served, the same as during 1985. The per-capita use has remained about the same for the last decade as the result of active conservation programs in many states that include the installation of additional meters and water-conserving plumbing fixtures.
The source and disposition of water for domestic purposes are shown in the pie charts below (or as a (1) GIF file , or (2) PostScript file (92Kb)). The consumptive use of water for domestic purposes during 1990 was 5,880 Mgal/d, or about 23 percent of withdrawals and deliveries.
In 1990, the South Atlantic-Gulf water-resources region had the largest self-supplied withdrawals for domestic purposes (figure 10 (GIF file)), (or as a PostScript file (629KB), whereas the California region accounted for the largest total of domestic withdrawals and deliveries (table 11). Self-supplied domestic withdrawals were fairly evenly distributed among the States ( figure 11 (GIF file) (or as a PostScript file (508Kb)). California, Texas, New York, Florida, and Illinois accounted for 44 percent of domestic water use because of large public-supply deliveries. (See figure 12 (GIF file)(or as a PostScript file (508Kb), ); table 12.)
