2015 Water Use- The USGS has estimated water use for the United States every 5 years since 1950. Estimates are provided for groundwater and surface-water sources, for fresh and saline water quality, and by sector or category of use. Total freshwater and saline-water withdrawals for 2015 were estimated to be 322,000 million gallons per day (Mgal/d; equivalent to 322 billion gallons per day), or 361,000 thousand acre-feet per year (acre-ft/yr). Freshwater withdrawals made up 87 percent of the total, and saline-water withdrawals made up the remaining 13 percent. Most saline-water withdrawals were seawater and brackish coastal water used for thermoelectric power.
Source: USGS