How Long Does It Take To Drain A Water Heater

How to drain a Water heater of Rheem and other brands

Your water heater is literally your lifeline in cold weather. For those of us who live in areas that remain relatively cooler throughout the year, it’s nearly impossible to imagine a single day without this useful appliance. However, despite our increased dependency on the water heater, seldom do we think about what would happen if we need to go even a single day without it!

While it may not always be possible to avert an issue altogether, the good news is that you can increase the lifespan of your water heater by following a simple rule once a year – drain and flush it. This post teaches you all about doing it so that you can keep your appliance going strong. 

The method of draining and flushing the water heater should be the same for all types of water heater, so the steps below should work on all kinds of water heaters.

How To Drain Water Heater?

How To Drain Water Heater

The water heater’s tank tends to get soiled due to the build-up and deposit of any sediment inside during the due course of time. As a result, it’s essential to clean the tank at least once in a year by draining a water heater. Here’s how you can do it:

Step 1: Turn the water supply off by closing the cold water supply valve situated above the water heater.

Step 2: Switch off the water heater. In case yours runs on gas, you’ll have to put its thermostat to the “pilot” setting. However, if it runs on electricity, you’d have to switch off the electricity from the main electrical box completely.

Step 3: Fix a hosepipe to the drain valve. You’ll have to find the drain valve of the tank, situated at the tank bottom, and then fix a regular garden hose pipe to the drain valve. Put the other end of the tube into a floor drain where the water can safely drain out. 

Step 4: Turn on a hot water tap situated closest to the water heater, preferably the one on the floor above. This would lighten up the pressure in the system and enable it to drain the water heater faster.

Step 5: Open the drain valve to drain the water heater sediment out of the tank. Exercise caution because the water will be hot. After all the water has completely removed out of the tank, turn on the cold water supply to the tank for some time. This would help clean out remaining sediment if any. Repeat this procedure until the water becomes completely clear. 

Step 6: Close the drain valve. Remove the hose pipe and turn the cold water supply on. It would trigger a refilling water heater. Turn off the hot water tap that was turned on earlier, after the cold water starts running from the pipe. Also, turn back the gas valve on from the pilot setting or in case of electric heaters, turn the electricity back on to the water tank.

Make sure to check again if the valve opening has been shut entirely so that there aren’t any accidental water leaks later. 

How Long Does It Take To Drain A Water Heater?

Factors such as the labor time and the size of the tank affect how long does it take to drain a water heater. If you have a tank capacity of 50 gallons and pressure of the hose allows you to flow water out of the tank at 10 gallons per minute, then you should expect the tank to be completely drained in 5 minutes. Similarly the answer to “how long does a 40 gallon water heater take to drain?” is 4 minutes. The process of draining your tank is usually a quick process and should not take more than 10 minutes.

How To Flush Water Heater?

How To Flush Water Heater

Just like draining, flushing a gas hot water heater often is equally important to clean it out of all the dirt and mineral sediments that build up within. You wouldn’t even realise that it’s due for flushing until there’s some problem one day and the heater stops working.

To save both cost and inconvenience in the long run, follow these simple steps at home to flush out your water heater at least annually. It only takes 20 minutes too!

Step 1: Turn off the thermostat – If you’re using a gas water heater, the thermostat can be easily found at the tank’s bottom. Although you could do away with just setting it to pilot mode too, but to be safe, it’s best to turn it off completely. In case of electric heaters, go to your home’s electrical box and turn off the main power switch that’s running the water heater.

Step 2: Turn off gas to the heater – Again, for gas hot water heaters, find the gas pipe that joins to the heater’s thermostat and pilot light. Switch off the valve. Skip this step if you just turned the thermostat to pilot setting. 

Step 3: Turn off the cold water supply – You’ll find the cold water valve generally at the top of your hot water heater. Switch it off.

Step 4: Turn on hot water: You can turn the hot water tap on in a sink or a tub but let it be on during the entire flushing procedure of the hot water heater. This would prevent vacuum formation in the lines during the hot water tank drainage step. 

Step 5: Turn on the pressure relief valve – This may not always be necessary, but doing so would facilitate water to flow more smoothly during drainage. Besides, you also get to test your pressure relief valve. Before you open the valve, make sure to place a bucket or container under the drainage pipe on the pressure relief valve. This is because as soon as you turn it on, the water would gush out with force. Also, you need to be careful since this water will be very hot. Allow the water in the hot water tank to cool down after the pressure relief valve has been opened.

Step 6: Attach the hose to drainage faucet – Turn on the pipe after you’ve placed the other end of the hosepipe out into a drain or into a bucket because once opened, the water would gush out with force.

Step 7: Drain the tank – Turn on the pipe and drain hot water tank sediment until the water runs clear. In case the tank has a lot of sediment, it may need to be drained out fully until empty.

Step 8: Flush the tank – Turn on the cold water pipe that leads to the hot water tank. Let the water run for some time until the one that flows out of the hose on the other end runs clear. It’s a good idea to wait for a while to be sure that the water is entirely clear because at first, the water may not be brown but may still have some sediment. In this case, continue flushing until the water becomes sediment-free. Then turn off the cold water faucet.

Step 9: After the water turns clear, you’ll need to finish up a few things that you started at the beginning of the process:

  • Detach the hose pipe and turn off the drainage faucet. 
  • Close the pressure relief valve.
  • Turn off the water flowing into the sink or tub that you first opened.
  • Turn on the cold water tap leading to the hot water heater.
  • Once the tank has been refilled, open the pressure relief valve again to allow any excess air to escape through.
  • Turn on the hot water faucet of the sink or tub to let the air out of the system. Make sure that cold water flows out of the faucet at this point and turn it off.
  • Turn the gas to your hot water heater back on in case you’d shut it off earlier.
  • In case the thermostat had been switched off, light the pilot light again and turn it on.
  • In case of electric hot water heater, flip the power switch on at the electrical panel.
  • Wait for the water to start heating up. It may take about 15-20 minutes. Turn on the hot water faucet to check if the hot water has started flowing.
  • Flushing of your hot water heater is successful and make sure to repeat the whole process the same time next year. 

How to Clean Sediment from Water Lines?

How to Clean Sediment from Water Lines

Another very common problem with your water heater is the build-up of sediment, such as rust or hard water minerals, which eventually end up clogging the water lines in your home and slowing down the water pressure in the faucets. Here’s what you can do:

  • Turn off the water heater and close the inlet valve. 
  • Fix a garden hose to the drain point of the heater with the other end into a floor drain.
  • Plug the faucet farthest from the water heater by placing a coin or rubber stopper in its aerator. Turn the aerator back on.
  • Turn on the cold water supply at the plugged faucet and let it keep running for about 40 minutes. Coldwater would force itself with high pressure into the hot water pipes and flush the sediment out through the garden hose.
  • Turn off the water tap. Remove both the plugs, detach the hose, open the inlet valve of the heater, and close the drain valve. Let the water tank fill and once complete, turn the heater back on. 


Summing Up

Your water heater maintenance, like any other appliance in your home, is an annual chore. It’s highly prone to catching sediment which can clog water lines, disrupt water flow, and cause inconvenience. Save the date for the next “clean water heater” session.

You also get Tankless water heaters, that would need lower maintenance than water heaters with tanks. If you plan on buying a tankless water heater, you could read our reviews on tankless water heaters to help you choose a good, long-lasting and cost-efficient water heater.

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