At least once every three months, drain water from the tank. Over time sediment builds at the bottom of the heater, which can hamper performance, and draining a gallon or so helps remove the sediment. 

You should also periodically inspect your water heater burner. The flame under the heater should appear blue with yellow tips. If it’s mostly yellow, or if it’s sooty under there, your flue may be clogged, which is a dangerous situation. Contact a professional to check it out. 

At least once every two years, have your water heater inspected by a service technician. He or she will also check the drain valve for signs of leakage, and the anode rods for corrosion.