Is Your Water Heater Expansion Tank Leaking? (We Have a Fix!)

Water heaters are a commodity in modern homes, and it can be stressful when something goes wrong. The expansion tank on a water heater is a critical component, and leaks are sometimes unavoidable. So, what does it mean when you find your water heater expansion tank leaking?

The most common reason for a water expansion tank leaking is that the pressure relief valve is damaged. Loose pipe fittings can also explain why your water expansion tank is leaking. Otherwise, you need to replace your water heater expansion tank if it is broken, and it costs an average of $361.

Loose pipe fittings are the easiest problem to solve if your water heater expansion tank is leaking. You can generally fix a leaking water expansion tank with plumber’s putty if the problem is minor. Follow along as explore the most common causes and solutions for a water heater expansion tank leaking.

The pressure relief valve on a water heater works to alleviate and regulate pressure. A damaged pressure relief valve can cause water to accumulate in your water heater expansion tank. Over time, too much water will build up in the expansion tank and cause it to leak.

A waterlogged expansion teak cannot work properly and you’ll need to empty the water heater and replace the pressure relief valve. Turn off the water heater from the breaker and the water supply so that it’s safe to work with. Place a bucket and towels beneath the drain valve and drain the remaining water from the tank.

Remove the damaged pressure relief valve with a wrench and screw the new one in place. Restore power to the heater and turn the water supply back on. If you find your water heating expansion tank leaking after this fix it indicates something else is wrong.

Loose pipe fittings can cause a water heater expansion tank to leak from the top or bottom in some cases. Inspect the pipes closely to identify which one is leaking and shut off the water supply and power. Dry the pipes with a towel or hairdryer if it is difficult to identify which fitting is leaking.

Open the pipe joints and clean the threads on the fittings with a plastic tool or fine brush. Apply waterproof plumber’s putty to the threads and reattach the old fitting. Replace the old fitting with a new one if it is too damaged or eroded.

Restore power to the water heater, turn the water supply back on, and see if the expansion tank still leaks.

A leaking water heater expansion tank doesn’t always mean that it is broken, but there are other signs to look for. You can tell that your water heater expansion tank is broken if the water pressure fluctuates between high and low. It is also worth it to replace your water heater expansion tank if multiple components are shot such as the drain valve and pressure relief valve.

Water heater expansion tanks only last for 10 years on average, but they can go bad before then. Replace your water heater expansion tank if it is nearly 10 years old and multiple parts need to be replaced. Otherwise, replace the expansion tank if it is broken and has holes in it.

Loose pipe fittings and a damaged pressure relief valve are the most common reasons for a water heater expansion tank leaking. Remove the old pipe fitting, clean the threads, and apply plumber’s putty to fix a leak. Replace the pressure relief valve if it is damaged because it can waterlog your expansion tank and make it leak.

Otherwise, you will need to replace the expansion tank if it is 10-12 years old or broken. It is nearly impossible to repair a water heater expansion tank that has holes in it.