Hot water tanks are designed to hold water for years and years, but flushing them should be part of your regular home maintenance schedule. Following our instructions listed below, this is a simple DIY task you can do yourself.

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Why should I flush my water tank?

Most hot water tanks have a significant holding tank that ensures there's plenty of hot water available when it's needed. However, because water sits in the tank continuously over time, naturally occurring minerals in the water, as well as sand and grit flushed from municipal water lines, can settle at the bottom of the tank.

The sediment buildup can potentially make it harder for your hot water tank to do its job. This puts your water heater at risk of failing sooner than it should. Hot water tanks should have a service lifespan of 10–12 years at least, but if the sediment isn't drained annually, their lifespan can be reduced significantly.

What about my gas hot water tank?

Sediment can also interfere with burner efficiency in a gas water heater. Have you ever heard cracking and popping noises during heating cycles? This is from the sediment in your tank.

Sediment in a gas hot water tank forms a thick, crusty coating. This diminishes the transfer of heat from the burner to the water in the tank. This wastes energy and, essentially, your money! This will eventually cause corrosion in the tank, which can lead to a huge mess when your tank starts to leak all over your floor.

Depending on your water source and the mineral content, both gas and electric water heaters should be flushed of sediment every 6 months to once per year to ensure optimal performance.

Can sediment affect my plumbing pipes or water?

The short answer is yes! The sediment or crusty material on the bottom of your tank can break free and end up getting lodged in the pipes that feed water to the rest of your home. This can slow the flow of water through your pipes and faucets. It can even risk plugging the drain valve on your hot water tank, making it impossible to drain it without a significant plumbing repair.

An important word of advice:

If you haven't flushed your hot water tank in a number of years, you may be better off having a Licensed Plumber do it for you. You run the risk of activating leaks. It's possible that the sediment that has been there for years has caused fissures in the bottom of the tank. The existing sediment is plugging those fissures, but once you drain and flush the hot water tank, it could remove the sediment that is 'sealing' the leaks.

Now I'm not suggesting that you shouldn't drain your tank, and I'm also not suggesting that if you haven't flushed it in a number of years, you're going to have a leak in your tank. By calling a Licensed Plumber to do the task, if it does leak, then you've got the right person on hand to deal with it.

Speaking from experience...

The reason I caution you with the word of advice above is that we had that exact scenario happen to a client. I published a brief guide to draining your hot water tank in a newsletter I wrote some years ago. My client had never drained the hot water tank in the 8 years he had lived in his home and thought it would be a good idea to finally do so.

He carefully followed all of the instructions and then called me in a panic because there was water leaking out onto his basement floor. Nothing was damaged because he didn't have a finished basement and the floor was concrete. However, he wasn't expecting a problem like this after following my thorough instructions.

When Paul, our Licensed Plumber, went out to investigate and inspect his tank, he found tons of pin holes all over the bottom of the tank! It was obvious they had been there for quite some time, and the sediment itself was preventing the leak. However, because there was so much sediment, his tank wasn't operating efficiently, and he had reduced water flow throughout his house.

Our client ended up having to get a new hot water tank, but in the end, he saved a considerable amount of money over time because his new tank was so much more efficient. Our client now flushes his hot water tank every six months.

One important first step

The first thing you need to do is locate the drain valve on your tank. It looks like a small outdoor faucet.

We strongly recommend turning off the gas or electricity to your hot water tank and allowing the water to cool to room temperature before draining it. This will take several hours. This is not necessary to drain the tank, but it is a safety precaution.

If you prefer not to wait the necessary time to allow all of the water in your water heater to cool, just remember that the water coming out of the drain valve will be very hot.

Steps to Draining Your Hot Water Tank

Turn off the gas supply or electrical power to your hot water tank. For a gas water heater, turn the thermostat to the 'pilot' setting. If it's electric, shut off the breaker or unplug the fuse at the electrical panel.
Turn off the cold water supply valve at the top of the water heater. This pipe should feel cold to the touch. If it feels warm, you've got the wrong valve.
Near the bottom of the tank, locate the tank drain valve and attach a standard garden hose to the drain valve. Be aware that some models may have a cover over the valve opening.
Place the other end of the hose in a floor drain or on a driveway where it can drain safely. If necessary, buckets can be used, but be careful not to be burned by the hot water as you work. Make sure the end of the hose is lower than the valve on the water tank.
Open the hot water tap nearest to the water heater, preferably on the floor above. This alleviates pressure in the system, allowing the water to drain quickly from the tank, much like removing your finger from the top of a drinking straw filled with liquid.
Open the drain valve and allow the water to drain from the tank. Again, the water will be hot if you haven't let it cool first, so use caution. Once all the water has drained from the tank, briefly turn the cold water supply on to the tank. This will stir up any remaining sediment. Repeat this process until the water runs clear.
Close the drain valve, remove the hose, and turn on the cold water supply. The tank will begin to fill. Go back to the hot water tap you opened earlier. Once cold water begins to flow from the tap, turn it off. Turn the gas valve back on from the pilot position or turn the electricity back on to the tank. Be sure to check the valve opening once it’s closed to ensure there are no water leaks.

What if my tank won't drain?

If your tank is draining slowly or not at all, try opening the temperature / pressure relief (TPR) valve on the hot water tank. This is located near the top of the hot water tank. It's usually a lever you can lift up or down, and there is a pipe that runs from it down to the base of the tank. Opening up the TPR valve may open up a potential vacuum inside the tank that's preventing water from draining.

It's also possible that there's so much sediment inside your tank that it's clogging the drain valve. This is where calling a Licensed Plumber is the best course of action.

To sum things up...

Although it's one of the most used appliances in your home, the hot water tank is also one of the most neglected. Maintaining your hot water tank is an easy task if you follow the steps above.

If you'd rather have our Licensed Plumber perform the maintenance on your hot water tank, please call us at 905-259-3344.