Plumbing experts recommend checking the heater tank's pressure release valve and flushing the tank every six months as part of routine hot water heater maintenance. The tank's anode rod should be checked annually and replaced if it is less than 1/2-inch thick or if it is coated with calcium.
The pressure relief valve is a safety device for releasing excess pressure from the water heater's tank. If it does not work correctly, the tank can over-pressurize and explode. Flushing the tank removes the buildup of sediment that can clog water lines and reduce the water heater's energy efficiency. Replacing the anode rod as needed helps to keep the inside of the tank from rusting out.