Tankless water heaters are available at The Home Depot, Lowe's and Sears, as of 2015. All three companies offer units that are powered by natural gas or electricity.
Available products include small units that heat up to 2 gallons per minute and whole-house devices that heat up to 5 gallons a minute, which is large enough to provide hot water for multiple devices running simultaneously. Tankless water heaters are typically more expensive to purchase than traditional hot-water tanks, but their operating costs are lower. Tankless units can last 20 years or longer, compared to the 10-to-15-year life expectancy of most hot-water tanks.