Free guides / Plumbing
How to Flush a Water Heater
Minerals settle at the bottom of a tank water heater, causing rumbling, less hot water and higher energy bills. A yearly flush keeps it efficient and can add years to its life.
Safety first
- The water is scalding. Let it cool or run hot water for a while first, and keep the hose outlet away from people and pets.
- Electric: turn off the breaker first. Gas: set the control to Pilot or Vacation. Never work on the gas line or burner; if you smell gas, leave and call the gas company.
Tools
- Garden hose
- Flat screwdriver
- Bucket
- Gloves
Parts
- None usually; a brass drain valve if the plastic one leaks
Step by step
Turn off the heat
Switch off the breaker (electric) or turn the gas control to Pilot/Vacation (gas).
Shut off cold water
Close the cold-water supply valve on top of the heater.
Connect a hose
Attach a garden hose to the drain valve at the bottom and run it to a floor drain or outside below the tank level.
Drain and flush
Open a hot faucet in the house to let air in, then open the drain valve. Let it run, then open the cold supply in bursts to stir up sediment until the water runs clear.
Refill
Close the drain valve, remove the hose, open the cold supply, and leave the hot faucet open until water flows steadily with no air.
Turn the heat back on
Only after the tank is full, restore the breaker or turn the gas control back to its setting. Heating an empty tank burns out electric elements.
When to call a pro
Call a plumber if the tank itself is leaking, the relief valve keeps dripping, or the water smells like rotten eggs even after flushing.
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