The way to maintain a residential hot water system is to maintain the water heater. One way to do this is to flush the water heater at least once a year. To do this, turn off the electricity to the heater or turn off the pilot light. Then, shut off the cold water inlet.
Attach a garden hose to the drain valve, and allow it to drain. Be careful not to let it drain into an area that cannot tolerate extremely hot water. This flushing allows sediment to leave the hot water heater, which extends its life.
After the water has drained, close the drain valve, and disconnect the garden hose. Close the pressure relief valve. After this, turn on all the hot water faucets in the house, and reopen the cold water inlet. Then, close all the hot water faucets, and turn on the hot water heater.
The pressure valve also needs to be checked from time to time. Follow the same procedure as flushing the tank, and place a bucket beneath the pressure relief valve. Pull the valve's trip lever, and listen for the sound of exiting air or wait to see if vapor or water comes out of the relief valve. If nothing happens, the pressure valve needs to be replaced after the tank is flushed.
The heater's anode rod also needs to be changed when it's used up.