WASHINGTON (CNN) -- Despite a steady increase in population, Americans are using about 10 percent less water than they did in 1980 because of conservation and water recycling, according to a new study by the U.S. Geological Survey.
The decline marks a reversal from annual increases in water over many decades, which peaked in 1980. The population increased 16 percent since then, say water experts.
"The nation is clearly using surface and groundwater resources more efficiently," said Robert Hirsche, chief hydrologist at the U.S. Geological Survey.
A Twenty Percent Drop Per Person
The study said Americans used 402 billion gallons of water a day for all uses in 1995, about 10 percent less than in 1980. The figure represents a 20 percent decline in water use per person during the 15-year period.
The USGS surveys water use every five years. Officials said they expect the downward trend in usage has continued since 1995.
But the biggest declines occurred in the 1980s, the study said, as industry and agriculture began to focus on conservation and water recycling.
In 1995, Americans used 500 gallons per day per person, about 2 percent less than the 1,620 gallons in 1990.Power Plants Biggest Users
Wayne Solley, a USGS hydrologist and co-author of the report, said the largest category of water use continued to be cooling at nuclear and fossil-fuel power plants, followed by irrigation.
Water use in both categories declined, with power plants using about 5 percent less water than in 1980 and farmers about 16 percent less.
Industrial water use has declined by about a third since 1980, to 29 billion gallons a day, largely because factories have begun to reuse much of their water. The use of recycled industrial wastewater more than doubled between 1980 and 1995, the study said.Conservation Remains Important
Residential water use also declined because of conservation and more efficient equipment.
One flush of the toilet in the early 1980s, for instance, equals four flushes today. Redesigned faucets and shower heads also better regulate water outflow.
Experts warn that saving water remains important, as many cities expand faster than their water supplies.
"Because of depleting aquifers, overburdened reservoirs and other environmental problems, the era of increasing water supplies is probably over," said Eric Goldstein of the Natural Resources Defense Council.