Water Heater Flush

Water Heater Flush

Step 1: Turn off the Water Supply

If you have an electric water heater, turn off the power at the breaker-box. If yours is a gas water heater, turn the thermostat to the "pilot" setting. Connect a hose to the drain valve located close to the thermostat, but don't open the valve yet. Turn off the cold-water supply that feeds the water-heater.

Connect Hose

Step 2: Drain the Hot Water

Inside your house, open up one of the hot-water faucets in one of your sinks or tubs. This will prevent a vacuum from forming in the lines. Go back to the water-heater, and open the drain valve to drain the hot water out of the tank. Make sure the far end of the hose is draining somewhere that won't be harmed by hot water. An outside driveway is ideal.

Open valve

Step 3: Flush out the Remaining Sediment

Once the water stops flowing out of the far end of the hose, turn the water supply back on. This will flush out any remaining sediment left behind in the heater. Once the water runs clear from the end of the hose, close the DRAIN valve. Don't forget to turn the hot-water faucet inside your house back off.

Let the water heater fill up, the heating element could possibly blow if there is no water in the tank. Some tanks may need to be completely full in order to prevent damage. When in doubt, always read the warnings and instructions on the tank label carefully because each tank may vary!

Step 4: Test the Pressure-Release Valve

See my TPR Valve section (TPR valve)


Water Heater Drain Pan information

504.7 Required pan. Where water heaters or hot water storage tanks are installed above the ground floor space, in attics or ceiling areas, or within the habitable space, the tank or water heater shall be installed in a galvanized steel or other metal pan of equal corrosion resistance having a minimum thickness of 24 gage, 0.0276 inch (0.70 mm). Electric water heaters shall be installed in a metal pan as herein required or in a high-impact plastic pan of at least 0.0625 inch (1.59 mm) thickness.

504.7.1 Pan size and drain. The pan shall be not less than 1.5 inches (38 mm) deep and shall be of sufficient size and shape to receive all dripping or condensate from the tank or water heater. The pan shall be drained by an indirect waste pipe having a minimum diameter of 0.75 inch (19 mm). Piping for safety pan drains shall be of those materials listed in Table 605.4.

504.7.2 Pan drain termination. The pan drain shall extend full-size and terminate over a suitably located indirect waste receptor or floor drain or extend to the exterior of the building and terminate not less than 6 inches (152 mm) and not more than 24 inches (610 mm) above the adjacent ground surface.

This is the 2007 code with the 2009 supplement