Water heater maintenance: flushing, anode rods and safety valves

A tank water heater works around the clock and gets very little attention until it stops. A few maintenance items, done on schedule, help it last longer and run more efficiently.

Flush the tank once a year

Minerals in tap water settle to the bottom of the tank as sediment. Sediment makes the heater work harder, can cause popping or rumbling sounds, and shortens the tank’s life. Manufacturer A. O. Smith says most tank water heaters need flushing at least once a year. Homes with hard water, such as much of the Southwest, may need it more often.

Check the anode rod

Inside the tank is an anode rod, a metal rod designed to corrode so the steel tank doesn’t. Once it’s used up, the tank itself starts to rust. A. O. Smith recommends inspecting the anode rod once a year. How long a rod lasts depends on your water: hard water and water softeners can wear it out faster. A plumber will recommend replacing it when much of the rod is gone, which costs far less than replacing the water heater.

Test the safety valve

The temperature and pressure relief valve (T&P valve) lets water out if the tank gets too hot or the pressure gets too high. A. O. Smith recommends that homeowners check it once a year and have a professional inspect it every five years. If the valve drips or leaks, have it looked at rather than capping or plugging it.

Other things a plumber checks

• For gas water heaters: the burner, gas connections and venting, so exhaust leaves the home safely.
• The thermal expansion tank, if your home has one.
• The thermostat setting. San Diego Fire-Rescue recommends 120°F or less to help prevent scalding, which also saves energy.
• Connections and the area around the base for leaks or corrosion.

Signs your water heater needs attention

• Rumbling or popping sounds while it heats.
• Rusty or discolored hot water.
• A rotten-egg smell from the hot water only.
• Water pooling around the base of the tank.
• Hot water that runs out faster than it used to.

Tankless water heaters

Tankless units don’t collect sediment the same way, but mineral scale builds up inside the heat exchanger. Most manufacturers recommend descaling (flushing with a cleaning solution) on a regular schedule, often yearly in hard-water areas. Check your owner’s manual for the interval.

How long they last

Tank water heaters often last around 8 to 12 years, depending on water quality and maintenance. If yours is in that range and showing the signs above, ask a plumber whether repair or replacement makes more sense.