Once a year
- Exercise the T&P valve. Pail under its tube, raise the lever briefly; a gush that ends when you let go is what you want. If it keeps dripping, the valve needs replacement.
- Flush sediment. Turn the heater to vacation or off, close the cold inlet, screw a hose to the bottom drain cock with its far end in the floor drain. Ease open the drain and let water run until it looks clear. Close the valve, open the inlet, and restore heat once the tank is full.
- Check the area. Look for rust, moisture or corrosion around fittings and the base.
- Check the venting. On gas units, look for loose or rusted vent sections and signs of backdraft such as soot.
Every few years
Have the anode rod inspected. The anode is a sacrificial metal rod that corrodes so the tank lining does not. Once it is mostly gone, the tank begins to corrode. Replacing it can extend the tank's life, if the tank is still sound.
Tankless units
Tankless heaters need descaling, especially in hard water. Service valves let a small pump cycle a mild acid through the exchanger. Clean the inlet filter screen, and have the burner and venting inspected.
Rented tanks
If your water heater is rented, the rental company is usually responsible for maintenance and repairs. Check your agreement before doing work yourself.
Safety
Never crowd a gas heater with stored items, especially flammables. Make sure a carbon monoxide alarm is installed nearby. Set the temperature to balance bacteria control and scald risk.