In 1961, the first practical plant for the conversion of seawater to drinking water was dedicated when President John Kennedy pressed a switch installed in his office in Washington D.C. It was built in less than a year at a cost of $1.5 million at Freeport, Texas by the Dow Chemical Co. The plant was capable of producing about a million gallons of water a day, supplying fresh water to the city of Freeport at a cost of about $1.25 per thousand gallons. The plant was opened 8 May 1961, by the Office of Saline Water, U.S. Department of the Interior. The large-scale evaporation method used then has now been replaced by reverse osmosis as scientific advances have produced special polymers suitable for use as filtering membranes.