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How to Flush a Water Heater

After years of use, your hot water heater has probably built up sediment deposits that are putting undue strain on it. If left inside the tank, the build-up can lead to costly repairs or break down the appliance entirely. Flushing a water heater is a simple chore that will save you in the long run. Here is how to maintain your device and keep hot water flowing.

What You'll Need

  • Garden hose
  • Screwdriver
  • Designated drainage area


Step 1: Turn off the Water Heater

If you have a gas heater, turn off the gas so the pilot is extinguished. For electric models, go to your circuit breaker and turn off the line supplying the heater. Once the power source is shut down, turn off the water. Allow 24 hours for the heater to cool some before proceeding to the next step.

Step 2: Connect the Hose and Prep the Drainage Area

Connect the garden hose to the drain valve, and run it to an area that won't be affected by the warm water and sediment. Remember that even though you've waited a day, the water in the tank will still be somewhat hot.

Step 3: Drain the Tank

Open the pressure relief valve, and use a screwdriver to open the drain valve. Then go to the floor above your tank to open a hot water tap. This will help the water drain quickly and smoothly.

Step 4: Close Valves and Resupply Water

Once all the water and sediment has completely drained, close the valves and turn the cold water supply back on. Wait and make sure that there are no leaks from the drain valve.

Step 5: Turn on Heating Element

Return to the tap that you opened in Step 3. Once cold water is running out of the tap, you can switch the breaker back on or turn on the gas. It's best to wait until there is some water back in the tank, as running the heat on an empty tank can potentially damage the heating element of the tank itself.