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How to Flush a Water Heater

Annual flushing removes sediment that causes noise, reduces efficiency, and shortens tank life. Know when it's safe and when to call.

ModerateCaution — hot water and scald risk

Tools You'll Need

Garden hoseBucketGloves (hot water)

Step-by-Step

1

Turn off the power or gas

Electric: turn off the breaker. Gas: turn the gas valve to 'Pilot' or 'Off'. Never drain a water heater while the power or gas is on — the empty tank can overheat.

2

Connect a garden hose

Connect a garden hose to the drain valve at the bottom of the tank. Run the other end to a floor drain, outside, or a bucket.

3

Open a hot faucet

Open a hot water faucet somewhere in the house. This lets air into the tank so it can drain.

4

Open the drain valve

Open the drain valve slowly. Water will flow out. CAUTION: water is hot. Let it run until the water runs clear — this may take 10–20 minutes.

5

Close and refill

Close the drain valve. Remove the hose. Open the cold water supply. Let the tank fill — you'll hear water running. When water flows steadily from the open hot faucet, the tank is full. Close the faucet.

6

Restore power or gas

Electric: turn the breaker back on. Gas: relight the pilot or turn the gas valve back on per the manufacturer's instructions. Do NOT turn on power/gas to an empty tank.

WHEN TO STOP

  • If the water coming out is rusty or has a lot of sediment, the tank may be corroding — flushing may not help long.
  • If the drain valve won't open or is clogged, don't force it.
  • If you smell gas at any point, stop and leave the area.
  • If the water is too hot to handle safely, wait for it to cool first.

WHEN TO CALL A PROFESSIONAL

  • The tank is 10+ years old and hasn't been flushed — sediment may be hardened and flushing may not help.
  • The drain valve is clogged or won't open.
  • You're not comfortable working with hot water or gas appliances.
  • Rusty water comes out — the tank may be corroding and need replacement.
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