Although the idea of reversing osmosis has been known for over 100 years, the practical application is a recent development. In 1962 the U.S Government funded the first R.O. plant which processed 1000 gallons clean water per day. Today, there are more than 3000 large R.O. treatment plants, each producing more than a million gallons of drinking water each day. In 1991, the U.S. Army bought 8,000 large FilmTec membranes to their mobile water purification units for troops in Desert Storm. In 1993, the U.S. Government bought another 6,300 large FilmTec membranes to purify flood water in the Midwest.