How To Replace A Water Heater Drain Valve

by Trevor Woods | Last Updated: July 27, 2020

If your water heater drain is leaking or won’t let you clean the tank, it’s time to replace the drain valve. A properly functioning drain valve allows you to service the water heater, flush the hot water tank, and replace the entire water heater.

If the drain valve fails, all the water stored in your hot water tank could potentially damage your home. It’s not a good idea to try and attempt to repair your water heater drain valve. If your repair fails, it could flood your mechanical room or basement.

Replacing a water heater drain valve is an easy way to upgrade your hot water tank and protect your property from water damage. We will show you what a drain valve is, what to look for when buying a replacement valve, and how to properly change your old water heater drain valve.

What Is A Water Heater Drain Valve?

The drain for your water heater is a plastic or brass valve located at the bottom of the unit. This drain valve threads into your hot water tank and has a shut off with an attachment point for any standard garden hose.

These features allow you to release water from the hot water tank safely and without flooding your home. A water heater drain valve holds back many gallons of water and its function is critical in cleaning, servicing, or replacing your water heater.

Without a properly functioning drain valve, you run the risk of damaging your water heater or your home.

When Do I Need To Replace My Water Heater Drain Valve?

It’s time to replace your water heater’s drain if the valve doesn’t allow for good flow when flushing the tank or the valve itself is leaking.

Consequentially, a valve that is clogged with debris and sediment is a result of poor water quality or a sign of the tank not being flushed regularly enough. Most factory-installed water heater drain valves are not designed to be easily serviced and it is best to replace the entire valve.

A leaking drain valve is also a cause for replacement. Drain valves made of plastic can become brittle over time. Weakening plastic can crack and cause a leak. Worn gaskets and seals inside of drain valves can also fail, resulting in dibbles and drips coming from your hot water tank.

Replacing your water heaters drain valve is the most reliable repair to fix a leaking valve. However, you can try to slightly tighten the existing drain valve to stop the leak. Be careful not to overtighten the drain valve. This may make the leak worse or run the risk of breaking a plastic valve off, whoops!

If your hot water tank has a brass valve you can try replacing the gaskets inside to stop leaks. But we do not recommend attempting this repair on plastic drain valves.

What Type Of Drain Valve Should I Buy?

When shopping for a replacement drain valve look for a quality brass valve that is lead-free and full port in design.

First off, brass valves are more durable and less prone to leak compared to plastic models.

Also, a full port ball valve is going to have a large diameter opening that will allow for fast draining and the ability to flush out large debris. This will make cleaning your water heater quicker and less prone to clogging.

Also, we recommend a drain valve that comes with a drain cap. This cap threads onto the garden hose connection and prevents any accidental dribbles or drips.

Water Heater Replacement Drain Valve

Full port ball valve with a large opening to allow faster draining and fewer clogs.

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Tools And Materials Needed

You’ll need a few basic hand tools to complete this repair:

• An Adjustable or Crescent Wrench
• Flat Blade Screwdriver
• Drain Valve

How To

This is a relatively easy job do you can do yourself in about 30 minutes. The hardest part will be waiting for your water heater to drain. Additionally, be careful when you drain your hot water tank, as the water will be hot and could scald you.

If at any point you are unsure of what you are doing please consult the Owner’s Manual that came with your water heater. Or if you feel uncomfortable with completing the repair, please contact a licensed professional for help.

1. Turn Off The Water Heater

Start off by shutting down your water heater. You can turn OFF the power to your electric water heater at the circuit breaker in your home’s electrical panel. Or turn the gas supply OFF for gas-powered water heaters.

Protect Your Heating Elements

Don’t try to drain your water heater with the power turned ON. You could cause serious damage to the heating elements.

2. Drain The Hot Water Tank

Next, attach a length of garden hose to the water heater’s drain valve. Run the hose from the water heater to a safe location outside or to a nearby floor drain.

Speed Up The Process

Don’t try to use a bucket to drain your water heater. There is simply too much water inside the tank.

Shut OFF the COLD water inlet valve and open a HOT water faucet to relieve the system pressure inside the tank. Now you can take a flat head screwdriver and open the drain valve.

The water should start to flow through the garden hose. Remember this water could be hot so make sure you stand back from the end of the hose.

No Flow?

If the water does not drain the drain valve may be clogged with sediment. This may be a time to call a professional for help.

3. Remove The Old Drain Valve

Remove the old drain valve with an adjustable wrench by turning the valve counter-clockwise. It’s a good idea to have a few rags or a towel to soak up any remaining water that dibbles out once you completely remove the valve.

4. Install The New Drain Valve

Prepare the new drain valve for installation by coating the threads in thread sealant or several wraps of Teflon tape.

White PTFE Thread Sealant Tape

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12/18/2023 04:15 am GMT

Wrap Like A Pro!

Wrap the Teflon tape in the direction that the drain valve will be screwed together. This will prevent the Teflon tape from unravelling when you thread the drain valve into the hot water tank. Wrap the Teflon tape in a clockwise direction as if you were looking down on the threads themselves.

Tighten the drain valve securely with the adjustable wrench in a clockwise direction. Once the new valve is installed, make sure it is turned OFF and in the CLOSED position.

5. Refill The Water Heater

Now it’s time to fill your hot water tank back up with water. Start off by opening a HOT water faucet somewhere in your home. This will allow the air inside the water heater to escape while you refill it.

Open the COLD water inlet valve to the water heater. Whoosh! You will start to hear the tank fill with water. As the water heater fills up, check the new drain valve for any leaks. If you notice a drip, tighten the drain valve a little more with an adjustable wrench. An additional quarter or half turn is all it usually takes.

When all the air is expelled through the open hot water faucet and there is a steady stream of water flowing, turn OFF the faucet.

6. Turn The Water Heater On

Turn the power supply back ON at the circuit breaker for electric tanks and turn ON the gas supply for gas-powered water heaters. You may need to relight your pilot as per the instructions on your hot water tank or follow our guide here.

Allow your water heater a few hours to heat back up. It’s a good idea to recheck the new drain valve for any leaks when the hot water tank is back up to operating temperature and once again in 24 hours. Tighten the drain valve as necessary. Done!

Conclusion

Being able to drain your water heater to make repairs or do routine maintenance will ensure that your hot water tank is heating efficiently and remains in good working order for years to come.

Regularly flushing your water heater will keep that new drain flowing and prevent future drain valve clogs. Now get back to enjoying your hot water!

Happy Plumbing!

Trevor Woods is the founder of Plumb University® and he started in the plumbing and construction industry in 1997. Since then, his mission is to make plumbing repair and maintenance easy for everyone. And each year, he continues to help more people with their plumbing installation, care, and troubleshooting.