How long does it take to drain a water heater?


By Evan Crowther

It’s essential to periodically flush your water heater to remove sediment. This will help it work more efficiently. Depending on the size of your water heater tank, it may take 10-15 minutes or even up to 45 minutes (or longer) to drain. 

Read on to learn more about what this process entails and how long it takes. 

Why should you drain your water heater?

The main reason to drain your water heater is to remove sediment buildup in the tank. Watch out for signs of issues with your water heater, such as:

  • Discolored, cloudy, or milky water coming from the hot water tap
  • Strange smells or noises (popping, hissing, etc.) coming from the hot water heater
  • Leaking or dripping tank
  • Water is taking a long time to heat up
  • Not enough hot water
  • Hot water running out too fast

Any of these signs may point to excessive sediment buildup — an indication that it's time to drain your tank.

How often should you drain your water heater?

Some experts recommend that you should flush your tank at least once or twice a year (every 6 months or so).

However, if you notice any of the signs mentioned earlier, it's probably time to drain your water heater ASAP.

How to drain a water heater in 9 steps.

Draining your hot water heater is relatively simple, but there are some safety hazards to keep in mind. When in doubt, don't hesitate to contact a professional plumber to drain (and even descale) your water heater.

You should always refer to your owner's manual when draining your water heater. However, here's a general overview of how to drain your water heater:

Step 1: Turn off your water heater.

If you have an electric water heater, it should have a power switch. If your heater doesn’t have a switch, use the breaker switch to cut the power.

For gas heaters, turn the gas off completely. Water heaters can often get as hot as 180 degrees Fahrenheit. To avoid burns, you may want to turn the heater off a few hours before draining.

Step 2: Turn off the water supply.

Turn off the cold water supply valve so you can empty the water heater. Most water heaters have a supply valve at the top of the unit.

Step 3: Connect a hose to the drain valve.

A standard garden hose will connect to the drain valve at the bottom of your water heater. Make sure the water heater is cool to the touch before attaching the hose.

Run the hose into a suitable drain outside of your home or into a bucket.

Step 4: Open a hot water faucet in the house.

Find a hot water tap that’s close to the heater, ideally one floor above the heater, and turn it on. This will relieve back pressure so the water heater drains more quickly and pushes out the sediment.

Step 5: Open the drain valve.

Once you have the nearby faucet running, it’s time to empty the tank. Open the drain valve to let the water drain through the hose.

Step 6: Flush the tank.

Once the water stops flowing out of the drain, open the tank’s cold water supply briefly to flush out any sediment. Check the water coming out of the hose to see if it’s clear. 

Step 7: Repeat if necessary.

If you notice excessive sediment, you can flush the tank again until the water comes out clear.

Step 8: Close the drain valve.

If you don’t see any sediment after opening the cold water supply valve, you can close the drain valve, turn off the water supply and remove the hose. Make sure the drain valve is completely closed to avoid a leak. 

Step 9: Turn the heater and water supply back on.

Turn on the water supply to the water heater. It’s best to let the water heater fill up before turning it on. Especially with an electric water heater, running it while the tank is empty can burn out the heating element.

Why is it taking so long to drain my water heater?

You may run into a few hiccups if you attempt to drain your water heater yourself. Here are a few issues and how to handle them.

Too much sediment.

Areas more prone to hard water tend to have more sediment buildup in the water heater. If an excessive amount of sediment has accrued in your water heater, this can make draining take longer. Over time, excessive sediment can also wear down the inside layer of your water tank.

If you’ve gone years without draining your water heater, consider hiring a professional to flush and descale it.

Clogged drain valve.

Sometimes, the drain valve itself can get obstructed by debris. This can make it take longer to drain the tank.

A water filtration system can help prevent debris from accumulating in your water heater, but periodic flushing is usually sufficient.

Faulty drain valve.

Like any piece of hardware, your drain valve can deteriorate over time. The knob may become difficult to turn. Or the valve may have an imperfect seal, resulting in leaks. You can cover your drain valve with a standard water hose cap to prevent it from leaking.

Hire a water heater professional near you.

Draining your water heater improperly can have disastrous (and expensive) consequences. What's the easiest way to tackle this project? Download Thumbtack today, and hire a water heating professional.


What is the fastest way to drain a hot water heater?

It’s quickest to use a garden hose to drain your water heater. Turning on a nearby hot water faucet can also speed up the draining process.

How much water should come out when draining a water heater?

You should empty your tank completely when you drain it. During normal use, the water heater fills up completely. So roughly 40 gallons of water will come out of a 40-gallon tank, although it may be less if you have significant sediment buildup.

How long does it take to get hot water after draining the tank?

How long you'll have to wait for hot water depends on what type of water heater you have.


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