If you have a tank water heater, flushing it at least once a year is really important in order to maintain its efficiency and extend its lifetime. This easy and relatively quick yearly maintenance will let you enjoy your expensive unit for as long time as possible at its ideal efficiency rate.

The process is pretty much the same for electric and gas tank water heaters. So, you can follow this guide no matter which type you own.

Before we jump in you should know that there is a risk associated to flushing a tank water heater that hasn’t been flushed for years. It is possible that a large amount of sediment is located at the bottom of the tank. If this is the case there is a chance that there are already micro-cracks on the inner wall of the tank and only the sediment prevents it from leaking. In this situation by flushing the tank you risk damaging the tank and having to buy a new unit.

So, if your tank water heater hasn’t been flushed for years – or you are not sure when it has been flushed last time (e.g. you have just bought a new house and you don’t have any info about it) – it is better to contact a professional plumber to investigate it.

If you own a tankless water heater, read this step-by-step guide we made on flushing a tankless water heater.

Why do you need to regularly flush your tank water heater?

No matter where you live you can be sure that water contains different kinds of minerals. The types and amounts of minerals may differ depending on the area you live in. There is no problem with these minerals from a human health perspective. However, the fact that water contains minerals is a problem when it comes to household items using water. Probably, the unit that is the most vulnerable to these minerals is your water heater – as it is continuously in contact with a large amount of water.

The problem is that over time sediment can build up inside the tank of your water heater. How much and how fast depends on the minerals content of your area as well as your maintenance habits.

Due to gravity sediment collects down at the bottom of the tank. Without regularly draining your water heater a large amount of concrete-like sediment will build up at the bottom of the tank. Over time it will prevent it from working properly. It does not only reduces the efficiency of the water heater but can also shorten the lifetime of it. It is because this concrete like mass is really corrosive and can eat through the metal tank.

The bottom line is that no matter where you live, sediment will collect at the bottom of the tank. By draining the water heater regularly you can flush the sediment out of it before it really builds up and starts eating up your expensive water heater.

Hopefully, now you understand why you should flush your water heaters at least once every year. It really is not a complicated thing to do and has many benefits.

Let’s see what steps you need to go through if you want to do it yourself.

If you are not comfortable doing it yourself you can always ask a plumber to do it for you. Click here to get a free quote from a pumbler in your area!

Flush Your Tank Water Heater Yourself – Steps to Follow!

Turn Off Your Water Heater

The first thing to do is to turn off the heat source. It applies for both gas and electric. In case of a gas powered unit it will prevent the burner from turning on. If you forget to do this you risk completely ruining your tank. What happens in this case is that the burner turns on while the tank is empty and continues trying to heat up the “non-existing” water.  As a result it can even melt the metal tank ruining it completely!

  • Electric unit: in order to do this you have to find the breaker in which the water heater is plugged in. Flip that breaker or simply unplug the unit from the wall.
  • Gas unit: the best thing to do is to turn the temperature to “Pilot” or “Vacation” mode. It is better than turning it off because if you turn it off, you’ll need to relight the pilot light after finishing the maintenance. So, by using this method it will be easier for you to set everything back to normal after you’re finished.

Turn Off Your Cold Water Supply Valve

After your heat source has been disabled the next step is to locate the cold water supply valve of the tank water heater. Now turn it off. Normally, you can find it behind the tank. In many cases it is on top of the tank. Once you’ve located it simply turn it to the OFF position.
This will prevent further water intake which is crucial to successfully execute the flushing.

Connect Your Garden Hose

Now that you’ve turned pretty much everything OFF, it is time to connect your garden hose to the drain spigot. It is located at the bottom of the tank of the water heater. Connect it tight but don’t overtighten it because you can damage the threads.

Open the Hot Water at One of Your Faucets

You are pretty much done by this step. There is not much else to do before you can drain your water heater. Go to one of the faucets in the house and open it on the hot water side only. Keep it open until the flushing process is over. You need to do this in order to let air get to the water heater from the faucet side. If you don’t do this water will not leave the tank even if you open the valve at the drain spigot.

Open The Valve at The Drain Spigot

This is actually the last step before the draining starts. Open the valve at the drain spigot to which the hose is connected. At this point you should hear water leaving the tank through the valve and/or air entering the tank due to the open faucet.

If you don’t hear water leaving or air being sucked into the system, there may be a blackflow preventer valve installed somewhere in the plumbing system. If this is the case the problem may be that opening a faucet is simply not enough. It is not a big deal though, you just need to do the next (extra) step.

Open The Pressure Relief Valve – Extra Step

The pressure relief is an important safety feature of your tank water heater. It is part of the system because if for any reason the pressure inside the tank gets too large, the relief valve will automatically open up and let the extra heat and hot water out preventing the tank from exploding.

You should be careful at this step as if you don’t do it correctly, you may burn yourself with the heated gas leaving the valve.

You should also make sure that it is seated correctly once you are done with the job.

Opening it is really simple: just gran the little arm situated at the top of the pressure relief and bend it straight up. Now you should hear air sucking into the tank and water starting to leave the tank through the garden hose.

Wait Until The Tank Gets Empty

This step will take some time. It is advised to check the water that comes out of your tank. Ideally it is clear water that doesn’t contain any sediment.

If it is not clear we recommend you to have it checked with a professional plumber because further investigation may be needed.

Don’t forget: the water coming out of the tank is really hot. So, make sure that nobody touches it or falls into it because they will get burned! Also, don’t put it on your grass or plants because it can damage it.

Depending on the size of your tank this step may take up to 15-25 minutes. Once there is no more water coming out of the garden hose you can be sure that there is no more water in the tank, it got empty.

Get The Sediment Out Of The Tank

Although the tank is empty at this point, you are not done yet. As you will experience the draining is a pretty gentle process. It means that simply draining the tank will probably not let you get rid of all the sediment at the bottom of the tank. This is why you need to do the next step.

Flush The Tank

Basically you need more power to get all the possible sediment out of the tank. For this you need to open up the cold water inlet for about 15-25 seconds. It will spray a lot of cold water into the bottom of the tank where the sediment may be located.

After 15-25 seconds close the cold water inlet. Wait 15-20 seconds. Remember: during this step the valve at the drain spigot is open so, once you open the cold water inlet, water will start leaving the tank through the garden hose again.

If during this process you check the water leaving the hose you will probably see some particulate in the water. It means that there was indeed sediment at the bottom of the tank and the flushing works because it leaves with the cold water.

Repeat this process until the cold water leaving the tank is clear. It indicates that all the sediment has been flush out of it. At this point you are pretty much done with the agitating flushes.

Most people will tell you that at this point you can refill the tank with water, set everything back and you’re done. We recommend you to go one step further just to make sure that the tank is completely clean.

Refill The Tank With Cold Water And Drain It

This is an extra step which although takes some time, really worth it.

  • Open the cold water inlet.
  • You should close the valve at the drain spigot – obviously, if you don’t do this, you won’t be able to refill the tank.
  • Also close the pressure relief valve.
  • Once you don’t hear any water flowing into the tank open the valve at the drain spigot and close the cold water inlet valve at the top of the water heater. Let all the water drain out of the tank. It will take another 15-25 minutes to completely drain again.

Refill The Tank With Cold Water

Congratulations! You are at the last step!

  • Close the drain valve and remove the hose
  • Open the cold water inlet again.
  • Open the pressure relief valve: you don’t want any air to get into your plumbing system while refilling the tank.

You should stand by the tank during this refilling process. Listen to the noises. Once you can hear that the water level inside the tank gets around half of the tank you can close the pressure relief valve. If you’re not cautious once the water level reaches the pressure relief valve, water will start flowing out through it.

Turn The Heater Back On And Let The Air Out Of The System

  • Once you have closed the pressure relief valve you can set the thermostat back to the desired temperature.
  • Open the hot valve at one of the faucets in the house just to make sure that all of the air gets bled out of the system.
  • Once the water is flowing normally, there is no more air leaving through it, you can close the hot water valve and you are finished!

That’s it! It really isn’t a difficult job to do and it will extend the life of your tank water heater by preventing the sediment build-up at the bottom of the tank. As mentioned earlier you should go through these steps around once every year.

Remember: if your tank water heater hasn’t been flushed for years (or you don’t know if it has been), flushing it may damage the tank.

So, if you are not sure, you are better off contacting a professional plumber in your area who will take a look at your water heater.