Water heater maintenance: flushing, anodes and more
A water heater is easy to forget until it fails. A few minutes of water heater maintenance each year keeps it efficient, quieter and safer, and can add years to its life.
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How do you maintain a water heater?
Water heater maintenance means flushing sediment from the tank once a year, testing the temperature and pressure relief valve, checking the anode rod every few years, keeping the temperature near 120°F, and checking the venting on gas units. Tankless water heaters need their inlet filter cleaned and the heat exchanger descaled, about once a year in hard water.
- Flush once a year
- Test the relief valve
- Check the anode rod
- Set to about 120°F
What to do, and how often
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Flush the tank
Yearly. Drains the sediment that makes heaters rumble and lose capacity.
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Test the relief valve
Yearly. Confirms the safety valve opens and closes.
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Check the anode rod
Every 2 to 3 years. Replacing a spent anode keeps the tank from rusting.
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Check temperature
About 120°F saves energy and prevents scalding.
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Check gas venting
Yearly on gas heaters. The vent must be secure and drawing properly.
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Descale tankless
About yearly, more often on hard well water.
Why flushing matters
Minerals in the water settle to the bottom of the tank as sediment. On a gas heater, the burner has to heat through that layer, which wastes energy and causes the rumbling or popping sound many older heaters make. On an electric heater, sediment can bury the lower element and burn it out. Flushing drains it out before it hardens.
Greenville Water is naturally soft, so tanks on city water build sediment slowly, but they still benefit from a yearly flush. Homes on wells often have harder water and more sediment. If a heater has gone many years without a flush, the drain valve can clog or leak when opened, which is a good reason to have a plumber do the first one.
The anode rod
Every tank water heater has an anode rod, a metal rod that corrodes so the steel tank does not. When it is used up, the tank starts to rust from the inside, which is the beginning of the end. Checking the anode every few years, and replacing it when it is worn down, is the single best way to stretch a tank's life. A rotten-egg smell from hot water can also come from the anode reacting with certain water, especially on wells; a different anode material usually fixes it.
Tankless water heaters
Tankless units have no tank to flush, but minerals can scale the heat exchanger, and an inlet filter catches debris. Descaling circulates a cleaning solution through the unit with isolation valves, which many installs include. Hard water means more frequent descaling; Greenville city water is soft, so many Upstate homes on city water need it less often. Our tankless repair page covers common error codes.
Let us handle it
Our VIP Prevention Plan includes a yearly whole-home safety inspection, which covers the water heater, relief valve, expansion tank and shutoffs. If your heater is near the end of its life, we tell you before it fails, so replacement is planned rather than an emergency.
Water heater maintenance: common questions
How often should I flush my water heater?
Once a year for most homes. Homes on hard well water may benefit from more often.
Can I flush my water heater myself?
Yes, if you are comfortable with it: turn off power or gas, attach a hose to the drain valve, and drain to a safe spot. If the valve is old or the tank has never been flushed, have a plumber do it.
Why is my water heater making a popping noise?
Usually sediment on the bottom of the tank. Flushing often quiets it.
What temperature should my water heater be set to?
About 120°F for most homes. It saves energy and lowers the risk of scalding.
How do I know if my anode rod needs replacing?
A plumber removes and inspects it. If it is worn to the core wire over much of its length, replace it.
Do tankless water heaters need maintenance?
Yes. Clean the inlet filter and descale the heat exchanger about once a year, more often with hard water.
Ready when you are
Tell us what's going on.
A Master Plumber will find the cause, explain it in plain terms, and put your options in writing before any work starts.
- A licensed Master Plumber on every job
- Serving the Upstate since 2010
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