How to Flush a Water Heater (Step by Step)
Sediment builds up in the bottom of every tank water heater, especially in hard-water areas. It insulates the burner, wastes energy, causes popping noises, and shortens the tank's life. Flushing it once a year takes about 30 minutes and is one of the best maintenance habits you can build.
Turn Off the Heater
For a gas heater, set the thermostat to "Pilot" (or off). For an electric heater, switch off the breaker — never run electric elements without water. Wait if you want cooler water, or work carefully with hot water.
Shut Off the Cold Water Supply
Close the cold-water inlet valve at the top of the tank. Open a hot-water faucet somewhere in the house to relieve pressure and let air in so the tank drains smoothly.
Connect a Hose and Drain
Screw a garden hose onto the drain valve at the bottom of the tank and run it to a floor drain or outside (downhill). Open the drain valve and let the tank empty. The water may be brown and gritty — that is the sediment you are removing.
Flush Until Clear
With the tank drained, briefly open the cold-water inlet to stir up and push out remaining sediment. Repeat until the water runs clear from the hose. In very hard-water areas you may need several rounds.
Refill and Restart
Close the drain valve, remove the hose, open the cold-water inlet, and let the tank fill completely (you will hear the hot faucet sputter then run steady — then close it). Only after the tank is full do you relight the gas pilot or switch the electric breaker back on.
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FAQ
Once a year is the standard recommendation; twice a year in very hard-water areas. Regular flushing can add years to the tank's life.
That sound is water boiling under a layer of sediment at the bottom of the tank. Flushing the tank usually quiets it.
Always unplug an appliance and shut off its water supply before servicing. This guide is informational and not a substitute for a qualified technician.