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How Do I Flush My Water Heater?

Unless your water temperatures aren’t optimal or you have no hot water, you might not give your water heater a second thought. While it’s simple to have the “out of sight, out of mind” attitude about this essential appliance, regular water heater maintenance is vital to prolonging its life and reducing energy costs. One of the most important maintenance steps is flushing, or draining, the tank. Knowing how to do this safely can help reduce your home maintenance costs and discover problems that could turn into dangerous or expensive problems.

Water Heater Flushing Frequency


The more hot water used in your home, the more often you should inspect and flush the tank. At minimum, inspect the water heater twice a year and flush it once a year. If there are up to five people in your home, it is a good idea to drain the tank every eight months and inspect it every four months. If there are six or more people in your home, drain the tank every six months and inspect it every four months.

When the hot water tank fills with water, minerals and sediments settle on the bottom. With time, the buildup could clog and ruin pipes, fixtures and appliances in your home. It may also compromise the heater’s components and energy efficiency.

It is important to note that if your home uses a well or the municipal water seems to have higher sediment levels, you may need to flush the water heater tank more often.

How to Drain a Water Heater Tank

  1. Turn of the power to the water heater. If the heater is electric, it might have a switch box or you might need to turn it off at the circuit breaker. If it uses gas, use the control knob to turn it off. Keep in mind that if the water heater uses gas, you may need to clean the burner and ports. If your tank has a recirculation pump, you will need to turn it off, as well.
  2. Allow the water in the tank to cool. Hot water in a tank can be 125°F to 190°F—temperatures that can cause serious burns. After turning off the power to the water heater, wait several hours for the water to cool or use the hot water that remains, like by taking a bath. The water in the tank should be cool before you flush it.
  3. Turn off the water supply at the cold-water shutoff valve. You can find this at the top of the water heater tank. It might have a blue knob. If not, it generally the supply line on the right.
  4. Attach a hose to the spigot found at the bottom of the tank. The opposite end of the hose should go into the floor drain, sump pit, utility sink, tub or even outside. The last thing you want is gallons of water flooding your home. If you want, you may also place the hose in a bucket outside so you can see the sediment that flows out from the tank.
  5. Open the hot water tap closest to the water heater. If the utility room has a sink, for example, you may open that tap. This helps relieve pressure in the system, allowing water to flow faster from the tank.
  6. Open the drain valve near the spigot. The valve might have a knob or you may need to use a screwdriver.
  7. Open the heater’s pressure relief valve. You’ll find this toward the top of the tank. Simply pull the lever up. The valve will make a hissing sound as air exits it. If it does not, it is broken. Replace it right away to prevent over-pressurization and a tank explosion.
  8. Allow the water to drain from the tank. Empty the tank completely.
  9. Flush the water heater tank with fresh water. After the water heater flush, turn the cold-water supply back on to stir up and remove the sediment that remains in the tank. Allow the water to exit the tank until it is sediment-free and clear. Turn off the cold-water supply line again. If you can’t get the last bit of sediment out, remove it with a wet/dry shop vacuum outfitted with an adapter and long ½-inch vinyl tubing.
  10. Close the hose’s drain valve tightly and remove the hose.
  11. Close the pressure relief valve toward the top of the water heater tank.
  12. Turn the on the cold-water supply line.
  13. Open all the hot-water taps in your home. After water flows from them well for about three minutes, close the spigots. At first, water may spit or gurgle from the faucets as air moves through the pipes.
  14. Allow water to fill the tank completely.
  15. Turn the power or gas to the water heater back on.

In general, water heater maintenance takes an afternoon. The time it takes to flush the water from the tank is well worth the extra years of service the unit will provide. If you notice a problem with your water heater or want an expert to perform the maintenance for you, get in touch with AAA Heating & Cooling today.