How to Drain a Water Heater


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Regardless of the type of water heater you own, it's generally a smart idea to drain it every six to twelve months to flush out the sediment build-up. This is an important maintenance task that will keep your heater running efficiently and lengthen it's overall service life. 

It may sound like a daunting task, but with the right tools and a bit of patience, it really isn't difficult. This step-by-step guide will help take you through the process so you can get the job done easily and efficiently. Flushing your water heater on a regular basis is arguably the most important thing you can do for your water heater.

Draining a water heater

Why Drain a Water Heater

A water heater needs to be drained for three reasons: Repairs, maintenance, and replacement. Let's take a look at each:


Many repairs require all or at least some of the water to be drained from your water heater's tank in order to change the part. If your temperature pressure and relief valve needs to be replaced, you'll need to drain the tank to a level that it is below where the valve is seated.

Heating elements, drain valves, and other necessary components of your water heater require your tank to be either fully drained or at least partially drained in order to make the repair.


Cold water enters your water heater from the main water line which contains gravel, sand, dirt, and other kinds of minerals such as calcium and magnesium. These items (called sediment) collect on the bottom of the tank and reduce the efficiency of the heater. The sediment insulates the burner (gas water heater) or heating element (electric) and slows the transfer of heat to the water. Since the water heater will need to expend more energy to heat the water, you'll notice your utility bills increase and your heater will not recover as quickly as it once did.

Sediment can also cause a blockage within the dip tube which brings the cold water to the bottom of the tank to heat. A sediment filter can help remove much of the sediment before it enters your water heater, but won't eliminate the need to flush your tank, although it will reduce the frequency to perform this important maintenance task.

In most cases, if you are flushing your tank you'll only need to partially drain your water heater.  

It should be noted that if you have an older water heater that has never or rarely been flushed it may be best not to perform this task. It's highly likely that the tank is corroded and the process of draining and refilling your water heater may actually cause it to leak.


If your water heater has reached the end of it's service life you'll need to fully drain the tank in order to remove it for disposal. A heater that is full of water is extremely heavy, but when empty, it is actually pretty light.

Hard hat and tool belt

The Tools You Need

Here's a list of the tools you need to drain your water heater:

Protective Gloves - You may want to wear protective gloves to guard your hands from not just nicks and cuts, but also the hot temperatures your water heater can generate.

Garden Hose - This is what you'll hook up to the drain valve in order to drain the water from your water heater. Any garden hose will do, as long as it fits the standard valve connection on your drain valve and it's long enough to reach to a sink, floor drain, or outside.

Flat Head Screwdriver - If your drain valve is tightened with a flathead screw, you'll need a screwdriver to loosen it so the water can drain through the valve.

Bucket (optional) - If you don't have an easily available floor drain (or sidewalk) to drain the water into, you'll want to have a bucket to catch the water from your heater. A 5-gallon bucket is a good choice, but remember, the larger it is the less often you'll need to empty the bucket.

Pliers (optional) - Having a pair of pliers nearby can come in handy if you see leaking at the valve connection between the drain valve and the garden hose. You'll need a tight connection and sometimes you just can't manage it with your hands, a set of adjustable pliers will help you get the job done.

Rapid Drain Tool (optional) - If you want to speed things up a little, you can use a rapid drain tool which uses CO2 or N2 or compressed air to send water through the tank faster than if it were to drain normally (which can sometimes take hours). These tools aren't necessary, but it can save time.

Hose draining water

How to Drain your Water Heater: Step-by-Step

Step-by-step instructions on how to drain your water heater:

Step One: Switch Off the Power to Your Water Heater

Before starting anything, you need to make sure your water heater isn't on. If your water heater is powered by electricity, turn off the switch near the water heater (if you have one) or turn off the circuit breaker at the main breaker panel. For gas powered water heaters, find your gas control knob and turn it off.

Step Two: Turn Off the Water Supply

On the top of the water heater is a pipe connected that supplies the heater with cold water. You should find a valve with either a lever or a dial on the pipe. This is the cold water supply valve. Turn the valve to shut off the water supply.

NOTE: Give your water heater at least a half hour to cool down, otherwise you'll be dealing with very hot water which may cause burns.

Step Three: Open a Hot Water Faucet

Open a hot water faucet somewhere in your house. This will allow the water within the tank to drain faster by preventing a vacuum from forming. Keep the faucet running while you drain the water heater.

Step Four: Check the Pressure-Relief Valve

The pressure-relief valve is located on the top or side of the tank, and it's connected to a pipe that runs down the length of the water heater. The role of the pressure-relief valve is to keep the tank from bursting as a result of excess pressure building inside the tank. It's a best practice to check this safety valve every time you drain your tank.

First, open the valve and listen for air to rush out, there may also be water leaking from the open valve. If you hear air or see water, the valve is working. If you don't, then stop the valve is defective and should be replaced, or you may need to purchase a new water heater. Since this is a safety device, you may want to consider hiring a professional to help you determine your next move.

Step Five: Connect the Garden Hose

Now it's time to drain your water heater. Put on your protective gloves and attach the garden hose to the drain valve. Make sure that you have as tight a seal as possible. Run the other end of the hose to a drain or outside, if you don't have a drain within reach of your hose, you can use a bucket. 

Step Six: Drain the Water Heater Tank

Open the drain valve, with a flathead screwdriver or by simply turning the dial, and allow the water to drain from the tank. If you're using a bucket, you'll need to occasionally close the drain valve and dump the bucket once it gets full. 

After you've drained about 5 to 10 gallons, check the water for sediment. If it's clear and sediment is no longer present, you can close the drain valve and begin filling your tank. However, if you're still seeing heavy sediment, continue draining and check after every 5 to 10 gallons.

If you're completing repairs, you can stop draining your tank at the appropriate level.

WARNING: The water draining from the water heater could be very hot. Avoid coming in contact with it and make sure you are wearing your protective gloves. Allowing the water heater sufficient time to cool down is a critical safety measure.

Step Seven: Flush the Water Heater Tank

Once the tank has completely drained, it's a good idea to flush out any sediment that's still inside. You can do this by opening the cold water supply valve again on the top of your water heater. This will flush new water into the tank and send the sediment through the hose and out of your tank.

Open and close the cold water inlet valve  several times to allow the pressure from the incoming water to flush any lingering sediment at the bottom of the tank. 

Step Eight: Close the Drain Valve

When you're satisfied the water heater tank is totally flushed, disconnect the hose and tighten the drain valve, then remove the garden hose.

Step Nine: Re-Fill Your Tank

Once the drain valve is securely closed, open the cold water supply valve on top of the water heater. As your water heater begins to fill with water, open a couple hot water faucets in your house. This will help flush the air out of the pipes, and when the water begins to flow through the faucets you'll know that the tank is full.

WARNING: Do NOT turn the power back on to your water heater until it has completely filled. Failure to do so, may damage the heating element on electric water heaters.

Step Ten: Turn the Power Back On

All that's left now is to reconnect your power supply and turn your electric or gas power back on. For most electric water heaters, that's just a matter of turning the circuit back on; for gas heaters, you'll need to relight the pilot.

In all cases, please refer to your manufacturer's instructions, or contact a licensed plumber if you need additional help. 

Watch the Video

Plumber with wrench in front of water heater

Get the Help You Need for Your Water Heater

As you can see, draining your water heater isn't a difficult task. However, if you still feel unsure, a licensed plumber in your area can easily do the job for you.

Regular maintenance, of course, is just the beginning of the journey. Draining your water heater every six to twelve months is vital upkeep, but the longer you have your water heater the more work you'll need to do to keep it running in peak condition.

That's where finding a professional licensed plumber comes in - search for a reputable one in your area, and you'll have a resource to call for any plumbing emergency, large or small.

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