For at least 25 years Industrialized nations of the west have been utilizing energy saving tankless water units for home hot water supply. More recently US industry has released compact, efficient producers of hot water that can supply shower, washer and other home needs simultaneously.
Standard water heaters of 20 -100 gallons must use large quantities of fuel to keep water hot 24 hours a day. In addition to the fuel and pocket savings, the new green models can earn a tax rebate worth several hundred dollars to offset the the higher costs of purchase and installation.