How To Drain And Flush A Hot Water Heater

Have your showers turned from comfortably steamy to frustratingly lukewarm? Or, has your water pressure dulled to a small trickle? When water heater problems pop up and you find yourself searching for a solution, draining the heater is a good place to start.

Over time, sediment builds up in the bottom of a water heater’s tank. This can cause the heater to lose efficiency. Since Arizona has very hard water, sediment build up happens much faster than in other parts of the country. Draining and flushing the tank is the only way to truly get rid of sediment buildup. Fortunately, this is easier than it sounds, and you won’t need to call a plumber to get the job done.

Step 1: Turn off the water supply

As with any job, the first step is to turn off the water. To turn the water off at the heater, you’ll need to locate the cold water supply valve. The cold water supply valve is located on or near your water heater, and is identifiable by its blue color. Turn the handle all the way to the right to ensure it’s off completely. If the handle is too stiff to turn by hand, use a pair of slip-joint pliers.

If you can’t locate or turn the supply valve, you can turn the water off to your whole home by locating the main shutoff valve. Common locations include near the hot water heater, in the garage, or in a crawlspace. Your home’s shut off valve may be also located outdoors. If it is, it’s likely buried underground near the street or sidewalk outside of your home, with a metal cover over it.

If you’re not sure where your main water shut off is, you have several options. One is to review the property inspection report you received when you purchased your home. Another option is to contact the city, or your home builder.

No matter the location, the main shutoff valve can be turned off by twisting clockwise with an adjustable wrench or by using specific tools such as a meter key.

Step 2: Turn off the heater

Now that the water is turned off, the next step is to turn off the heater itself. This process differs depending on if your heater is powered by gas or electricity.

  • If you have a gas water heater: Turn the thermostat so that it’s on the “pilot” setting.
  • If you have an electric water heater: Locate your breaker box and turn off the electricity.

Even with the heating elements turned off, the water in the tank can stay dangerously hot for a long time. To make sure you don’t get scalded, wait overnight for the water to cool before proceeding to the next steps. If you don’t have time to wait, take extreme caution to ensure that you drain the scalding water away from where it may come in contact with someone.

Step 3: Open the nearest hot water tap

To alleviate pressure, open some of your home’s hot water taps. Preferably, ones that are on the floor above the heater. This step allows the water to drain quicker from the tank, by making sure a vacuum doesn’t form in the pipes. The taps will remain open during the rest of the process.

Step 3: Attach hose to drain valve

For this step, you’ll need a standard garden hose. Near the bottom of the tank, you’ll find the drain valve. Open the valve and attach one end of the hose to it and place the other end in a place it can drain safely, like a floor drain, your driveway or your front yard. If you don’t have a garden hose, you can drain the water into an empty bucket instead. However, be prepared to empty the bucket frequently, as the tank contains many gallons of water.

Step 4: Drain the tank

With all the preparations complete, it’s time to drain the tank. Open the drain valve and allow the water to flow. You may need to loosen the valve with a flathead screwdriver. Generally, this step takes 10 minutes or less. The size of the tank dictates exactly how long it’ll take to drain. For example, if you have a 50-gallon tank flowing at 10 gallons per minute, you can expect for it to fully drain in about 5 minutes.

Step 5: Flush the tank

Once all the water is drained from the tank, you can flush it a few times to clear out any remaining sediment. To do this, turn the cold water supply valve back on for a few seconds at a time, until the water runs clear. Then, turn the water off again.

Step 6: Cleanup

Once the water runs clear, the process is complete. The last step is to tie up any loose ends, make sure your heater is powered back on, and do the following:

  1. Close the water heater drain valve.
  2. Turn the cold water supply valve back on.
  3. As the tank begins to fill, return to the hot water tap you opened earlier. Run it until there are no air bubbles. When normal water flow returns, you’ll know the tank is full.
  4. Once the tank is filled, restore the power to the main water supply.
  5. Enjoy your sediment-free hot water!

More water heater maintenance tips

Draining your water heater every 6 months is one of the best forms of maintenance. Here are more tips you can use to keep your heater well-maintained and running at its best.

Lower the temperature

By default, many manufacturers set water heater thermostats to 140 degrees Fahrenheit. However, for the good of your heater, we recommend lowering it to 120 degrees Fahrenheit. Not only does this temperature pose a lower risk of scalding, it also slows the rate of mineral buildup and corrosion.

Add insulation

If you have a newer water heater, it’s likely already insulated. But, for older heaters and ones that lack insulation, adding it can cut standby heat losses by 25-45%. This can save you anywhere from 7-16% annually on your water bills, according to the U.S. Department of Energy. Many hardware stores sell pre-packaged insulation that can easily be cut and installed around your water heater.

Recognize the early signs of water heater failure

No water heater lasts forever. Recognizing the early signs of heater failure helps you avoid a costly emergency, and gives you time to work with a plumber on selecting a replacement.

The early signs of water heater failure include:

  • Leaks
  • Corrosion
  • Low supply of hot water
  • Scalding water, or water that’s too hot
  • Buzzing noises
  • Burnt out pilot light
  • Complete loss of hot water supply

If you notice any of these signs, contact a plumber before the problem gets worse.

For water heaters and more, contact Chas Roberts

Our plumbers know the ins and outs of your water heater, but our knowledge doesn’t end there. From common repairs to custom installations, we can address all your plumbing and HVAC needs. Contact us to get started.