How to Flush Hot Water Heater

How to flush hot water heater and why flushing article will help you keep your heater performance high, remove sediments, bad odor and bacteria that causes it.


Periodic tank flushing is necessary and recommended by every manufacturer (Rheem, AO Smith, Bradford White) and for every type of water heaters; tankless, tank type, electric, gas and solar.

How to flush hot water heater article will also help you with the chlorination process to clean the heater from the rotten egg odor, discolored water condition and eliminate bacteria.

Why and when to flush hot water heater

  1. Do flushing because hot water is rusty or brown in color. Brown color is usually the sign of the material buildup inside the tank due to rust from plumbing, water softener resin, sand and clay sediments and other earth materials. If your home plumbing is plugged on the water mains, usually constructed of steel or cast iron pipes, there is a lot of rust coming into the tank.

  2. Perform flushing because of the rotten egg smell. The rotten egg odor is actually a hydrogen sulfide odor caused by bacteria. If you succeed to eliminate bacteria you will be able to control the odor.

  3. Water heater flush is necessary to remove the sediment and lime build-up. Lime and sediment build-up is the major cause of the slow and inefficient water heating, rumbling and pounding noise and that is why you should use the softener, sediment cleaner or delimer solution in combination with tank flushing.


When to flush

If you are asking yourself how often to flush hot water heater, simple follow the manufacturer recommendation which is usually once every 6 months to one year.

Flushing schedule depends on your local water condition also. If the water condition is harder, it contains more minerals, you may need to flush more often. Minimum requirement is to drain 1 to 2 gallons from the drain valve monthly.


Step by step guide

  • If using gas heater turn the gas valve off. On the electric heater, turn off the electricity.

  • Shut the cold water off to the heater.

  • Open a hot water faucet.

  • Drain the heater by connecting the garden hose to the drain valve.

  • Turn back on the cold water into the heater.

  • Allow the water to run through the heater and out of the drain valve. Flush the heater for five or ten minutes.

  • Close the drain valve and keep the tap open while refilling the tank heater.

  • Once the tank is full follow the procedure found on the label and instructions how to run the heating.

Or watch the video...


Flushing with chlorine

Flushing the water heater through the drain valve provided at the bottom of the heater, with the appropriate dissolver like chlorine is one way to control and eliminate bacteria from your heating system. Below is a proper procedure for chlorinating a heater, recommended by Bradford White manufacturer:

  • Turn off the water, power and/or gas supply to the heater.

  • Use drain valve located at the bottom of your heater and drain several gallons.

  • Pour a 1/2 to 1 gallon of bleach into the water heater through the hot water outlet opening.

  • Install new anode rod or bring the old one back if it is still functional.

  • Re-connect the hot water supply line to the outlet on the heater.

  • Turn on water supply and draw water to every hot water fixture in your home until the chlorine smell is detected. Keep in mind that all plumbing lines must receive treatment.

  • Once the chlorine odor is noticed, turn off the faucets and allow the bleach to sit in the heater and plumbing lines for a minimum of 3 hours, a full day is desired.

  • Turn on and draw water at each tap in your home, to flush all chlorine from the piping, till the odor is no longer present.

  • Turn on the power and/or gas supply to the heater.

Water softeners, long periods of no water movement or if using well supply, are all the potential causes of the bacteria presence. This is why shock-chlorination of the heating system is recommended. Combine the above process and flush hot water heater often if you have heavily infected system.


Related articles

water heaters