Flushing a Water Heater

Clearing Sediment

Cleaning sediment from out of your water heater is not particularly difficult, here is how to do it.

  • If your water heater is gas, set the gas valve to “Pilot” to prevent the burners from coming on while you are flushing it. If your heater is electric be sure to turn off the circuit breakers.
  • Connect a garden hose to the drain valve at the bottom of the tank.  Make sure the outlet of the hose is in a safe area away from pets and children to prevent scalding from the discharged water.
  • Close the shut off valve on the cold water inlet to the water heater.
  • Carefully open the pressure relief valve (T&P Valve) by lifting the lever to the valve; this valve may be located on the top or side of the tank.
  • Leave the valve open.
  • Open the drain valve at the bottom of the heater to allow the water to flow out through the garden hose.
  • If the sediment is clogging the drain valve then try closing the pressure relief valve (T&P Valve) and turn the cold inlet valve back on to “power flush” the sediment out.
  • Sometimes the built-up sediment in the tank may hardens into large chunks that can restrict the drain valve opening. If so, then wait until everything cools down, remove the garden hose from the drain valve, remove the valve if necessary, and use a long screw driver to break up the clog. This can be a very messy process. However, a necessary one if water heater is to be flushed.
  • When the water from the garden hose runs clear you are finished.
  • Close the drain valve at the bottom of the tank and remove the garden hose.
  • Close the pressure relief valve, if it is still open, and turn the cold water valve on the inlet side back on.
  • Open a hot water faucet in your house to release any air from the line.
  • Turn the heater back on at the breaker for electric, and with gas units re-light the pilot light if necessary.

You have now flushed your water heater.