A tank water heater is a storage appliance that keeps roughly 30 to 80 gallons of water hot inside an insulated steel tank, using a gas burner or electric elements. Cold water enters through a dip tube at the bottom, hot water leaves from the top, and a sacrificial anode rod and T&P relief valve protect the tank.
Why it matters to you
Most U.S. homes heat water in a storage tank, and tanks typically last about 8 to 12 years, so the tank's age is the first thing to check when hot water runs short or water appears at the base.
Practical guidance
Flush the tank once a year, test the T&P relief valve, and have the anode rod checked every few years. If water is pooling at the base, close the cold-water supply valve and turn off the power or set the gas control to off before arranging a repair visit.