How to Replace a Drain Valve - DIY Instructions

Learn when, why, and how to replace a drain valve on a water heater. What is a drain valve, and what are the main reasons for its replacement? What to do when it is stuck, clogged, or broken? Is it dripping or leaking? Draining tips.

What is a drain valve?

Drain valveDrain valve

A water heater drain valve is a small valve located at the bottom of the heater designed to drain water from the heater’s tank for cleaning and maintenance purpose. 

It is found on both electric and gas type; it has two threaded ends (typical size of ¾”), one to screw it into the heater and the other to attach the garden hose (for draining). The valves can come with the handgrip handle or screw head to open or close.

The valve is made of plastic, usually present on the economy models, or brass found on more expensive units. The drain valve can be easily replaced, so if it is damaged, get the one made of brass, which is more reliable and can last longer. They usually cost around $10.

Why is draining important?

Draining a water heater, including flushing, is part of regular maintenance. We drain water heaters to remove debris, such as sediment buildup and rust, or when replacing some parts. When combined with flushing, mineral deposits at the bottom of the tank can be removed from the heating system, so the heater can perform better, have better efficiency, and last longer.

What are the reasons for the drain valve replacement?

If your water heater drain valve is leaking, is worn out, or doesn’t allow good water flow, it is time to replace it. Other reasons for replacing a valve is if you want to have a better quality one, such as brass, or even a ball valve, for easy handling and longer life.

What if the valve is stuck?

If your water heater is heavily affected by the hard water condition and excessive sediment buildup, and the drain valve is stuck and clogged or even broken, you might have to use some tools to unclogged it or remove it.

Use a hack saw to cut the valve, hammer, and screwdriver to break up deposits and chisel out the plastic. Some experts recommend using the wire coat hanger to loosen the debris by inserting it into the valve and moving it in a circular motion.

WD-40 spray probably won’t help in this situation.

Be careful not to damage the metal threads on the heater.

How to replace a drain valve

Replacing a drain valve is an easy DIY job. It doesn’t require any special skills or tools. It will take you approximately 30-60 minutes, or longer, if the valve was heavily clogged and it is hard to remove it.

Note: Water from the tank might be hot, so be careful as you might get scalded.

Recommended tools

  • Adjustable wrench
  • Screwdriver
  • Teflon tape/pipe sealer
  • Garden hose
  • Bucket
  • Cloths / towels

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  • Turn off the power to your water heater on the electric panel and breaker.
  • Turn off the gas supply (if applicable).
  • Turn off the water supply on the shutoff valve near the heater.
  • Attach one end of the garden hose to the drain valve and run the other end to the nearest drain or outside if possible.
  • Open the hot water tap, which will help in draining and release the pressure inside the tank. To avoid the pressure buildup, you can also open the temperature and pressure relief valve (T&P).
  • Open the drain valve using the screwdriver if it uses the screw handle, or rotate the handle.
  • Once the draining stops, remove the hose.
  • Use the adjustable wrench and remove the drain valve. There will still be some water coming out most often, so use a bucket to collect it.
  • Take a new valve and put some Teflon tape or a pipe sealer on its threads.
  • Put a new valve in the provided hole of the heater, and make sure to tighten it enough to prevent leaking.
  • Make sure that the valve is in the closed position so you can fill the tank.
  • Open the hot water tap.
  • Open the shutoff valve to let the cold water flow inside the tank.
  • Check the connection for leaks.
  • Close the hot water tap once the flow is established.
  • Resume the power to the heater, including the gas supply. If the gas water heater has a pilot light, you might have to relight it, using the instructions found on the sticker.
  • Check for leaks again.

Note: Don’t be surprised if you see debris coming out of the drain valve. Particles could be the sediment buildup, lime-scale, rust, sand, even pieces of the dip tube.

When the water heater is drained out, take advantage and inspect a dip tube and anode rod, and replace it if necessary.

Can you replace a drain valve without draining?

Yes, you can, but it is recommended only if the heater is located in places such as a garage, basement, or any other room with a drain and where a potential leak can’t damage the property. A water heater should be off and water inside the tank cool. Make sure to have a towel and drain valve ready. Remove the old valve and quickly install a new one.


It is recommended to inspect the rod once a year to keep the tank safe from rust. The rod is submerged in the water, and due to the aggressive water action is eaten away over time. If you find the rod depleted by 1/2 of its volume or more, it is time to replace it.

Replacing a water heater drain valve, as it can be seen, is not hard and time-consuming, but it still should be your last resort. If you want to avoid the hassle of calling a plumber, buying a new valve, and the entire process described in the above step-by-step guide, try first to tighten the valve using the adjustable wrench. When replacing an old or broken valve, aim for the strong, tamper-proof, and low restriction brass drain valve. It will allow faster draining, reduction in service time, and longer life.

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