Why Your Water Heater Is Leaking From The Top and How to Fix It

A leaking water heater can cause a serious mess – but rest assured that a leak coming from the top of your water heater is much better than a leak from the bottom!  

The most common reason a water heater leaks is because of a faulty seal where two pipes are connected or where a pipe goes into the water heater but they could be caused by a few other things as well such as faulty or broken valves, a loose gasket or a problem with your extension tank. The fix could be as simple as tightening a screw or may require the help of a professional.

If left unattended, that leak coming from the top of your water heater can cause energy waste, mold growth, and even structural damage in your home. So it’s best to get leaks fixed right away.

In this article, I’ll point out some of the most common causes of leaks coming from the top of your water heater and how to go about fixing them.

Reasons Your Water Heater Is Leaking from the Top

There are several reasons why water might leak out of the top of your water heater. Some of them are minor and easy to fix while others require professional help. If you’ve found a leak in the top of your water heater, check to see if any of the following is causing the leak. 

Loose fittings

At the top of your water heater, you will find one inlet fitting which carries cold water into the tank and one outlet fitting which carries hot water out of the tank and into your house. These fittings can be a common spot for leaks if they are loose.

If your inlet and outlet fittings are made of flexible metal tubing rather than hard, rigid pipes, they are not likely to last as long and are more prone to leaks.

Loose fittings
Loose fittings

Fittings can come loose wherever a pipe intersects with another pipe, but most commonly loosen over time where the fitting goes into the water heater. 

Corrosion of the pipe fittings can also cause leaks so when inspecting them, make sure to keep an eye out for signs of corrosion. 

Faulty outlet valve

If the fittings on the top of the water heater are all tight and snug, and the water heater is still leaking, it’s possible that the outlet valve itself is faulty. 

Remember, the outlet valve controls the flow of hot water out of the tank and into the pipes going into your house.

Faulty outlet valve
Faulty outlet valve

When the valve malfunctions, it allows too much water into the pipe and causes the pipe to become blocked which then leads to leaks. 

Your temperature and pressure value is broken

The temperature and pressure valve, also known as the T&P valve, is a safety feature added to water heaters to minimize the risk of explosion.

It works by letting water and steam escape when it detects too much pressure, or too high of temperatures in the tank so that those don’t build up and possibly cause the tank to explode.

Your temperature and pressure value is broken
Your temperature and pressure value is broken

It’s a great safety feature, however, over time sediment can build up around the valve which can keep it from properly closing. If the temperature and pressure valve is not opening and closing properly, it could cause a leak.

Your heating element gasket is loose

If you have an electric water heater, the heating element is held in place by rubber seals called gaskets. There is typically one located at the top of your water heater, and one at the bottom.

Your heating element gasket is loose
Your heating element gasket is loose

These gaskets help keep warm water inside the tank. However, if they become worn down, they won’t seal properly anymore. This can allow cold air to enter the tank, leading to freezing temperatures. When that happens, the water heater can start to leak.

Your anode rod screw is loose

The anode rod is a long rod, typically made of zinc, aluminum, or magnesium, and its purpose is to prevent corrosion in your water heater’s tank by attracting particles and minerals and corroding itself rather than the tank.

Your anode rod screw is loose
Your anode rod screw is loose

It is screwed into the top of the water heater with the anode rod screw. Over time, the anode rod will rust and cause the screw to loosen.

Your expansion tank is overflowing

If you have a closed plumbing system in your house, you most likely have an expansion tank on your water heater. The extension tank is there so that when the water heats up and expands, it has somewhere to go to avoid pressure buildup.

It is usually installed directly above the primary tank, but could technically be installed anywhere on the cold inlet line. 

The expansion tank can overflow if there’s too much pressure in the water system.

Leaky expansion tanks can also be caused by corrosion inside the system which occurs when water molecules break down metal parts over time.

How to Fix Your Leaking Water Heater 

To prevent leaks from causing major damage, make sure to regularly inspect your water heater. If you detect a leak, repair it immediately.

Otherwise, you could end up wasting thousands of dollars fixing a problem that could have been easily fixed earlier. Take a look at the following fixes for some of the common causes of leaking I mentioned above.

Step 1: Turn Off the Water Heater

Turning off the water supply before starting to work on your leaking water heater will always be the first step.

If it is a gas water heater, find the valve on the side of the tank and simply turn the valve to the off position. 

If it does not have a valve on the side, it is electric. To turn off an electric water heater, go to the circuit breaker and locate the breaker giving power to your water heater, and shut it off. 

Turn Off the Water Heater
Turn Off the Water Heater

Next, shut the water off. To turn off the water, look for a valve on the inlet and outlet pipes and turn it off. If you can’t find a valve there, turn off your house’s main water supply. Turn on your sink’s hot water faucet to relieve the remaining water pressure in the pipes.

Step 2: Find the leak

Some leaks may be obvious if there is water dripping from a certain point. Others, however, may take a bit more effort to find. 

You’ll want to do a full inspection of both inlet and outlet fittings, all the valves on the water heater, and the anode rod screw to start with. Let’s take a look at how you can check for leaks in each common area in more detail.

Pipe fittings

Using a step ladder, get up to where you can get a good look at the pipe fittings at the top of the water heater. Check any joints where two pipes connect for any signs of leakage. Make sure to take a close look at where the inlet and outlet valve go into the tank. 

Signs of leakage could either be water visibly leaking out or any signs of corrosion. If there was corrosion you would likely see rust around the fittings or a white powdery substance that would be caused by the water leaking. 

Leak in your pipe fittings
Leak in your pipe fittings

If you spot any leaks, tighten the joint with a wrench. You can also consider using some lumbers tape around any threaded fittings. If you find a loose fitting in a hard-to-reach spot, you can use pliers to grab onto the fitting and pull it toward you.

Faulty outlet valve

If the outlet valve malfunctions, there is no fixing it. You’ll need to replace it altogether. 

To replace the valve yourself, you’ll just need the right size pipe wrench or an adjustable one. Make sure you have the power and water supply shut off before removing the old valve and replacing it with the new one.

Temperature and pressure valve

If there is a leak coming from the T&P valve, you could have a more serious problem on your hands.

It could either be leaking from the bottom of the valve where it screws into the water heater, or from the piping attached to it. 

Either way, if you suspect your temperature and pressure valve is leaking, it could mean there is too much pressure in your water heater and it’s best to call a professional for help.

Since it is such an important part of keeping the pressure in your water heater at a safe level to avoid explosions, you don’t want to get it wrong.

Heating element gasket

To check for a leak here, you may need to remove the cover on the water heater by unscrewing the screws on the front of it. Push the insulation to the side and look for any signs of leaks. 

If it is leaking where the heating element goes into the tank, it’s probably a problem with the gasket. Rather than trying to fix or tighten the gasket, I would recommend replacing it.

Calling a pro might be best on this one, but if you decide to replace the gasket on your own, you’ll have to remove the heating element first which means you will have to drain the tank, remove the heating element using a socket wrench, and remove the gasket. Give it a good wipe-down before putting the new gasket on. 

Anode rod screw

If you notice dripping or bubbling water coming from the top of your hot water heater, it could mean a leak caused by the anode rod or a loose anode rod screw.

You can tighten the screw using a socket wrench and see if that fixes the problem. If not, you may need to replace the entire rod. 

Check the expansion tank

The expansion tank could be leaking from either side of the pipe that connects the expansion tank to the water heater. It could also be coming from the tank itself which would mean that corrosion is occurring in the tank. 

A leak from the pipes may be an easy fix because you can tighten the connections with a wrench or use some plumbing tape on the threaded fitting. The latter, however, would require a replacement of the extension tank immediately which would be best done by a certified plumber.

If you decide to replace your expansion tank yourself, check the manufacturer’s instructions and make sure that you follow those guidelines carefully. Otherwise, you run the risk of causing further damage.

When Should You Call a Professional?

Some of the fixes I mentioned above are not going to require the help of a professional. You don’t need to call a plumber to help you tighten a loose pipe fitting for example. Just grab your wrench and give it a bit of a tug. 

On the other hand, for some of the big fixes, it may be best to call a plumber. Here are a few of the things I would suggest calling a professional for help with and an estimate of what they might cost:

  • Replacing the T&P pressure valve – between $50 and $300.
  • Changing the heating element gasket – between $100 and $350.
  • Changing the anode rod – between $150 and $300.
  • Extension tank replacement – between $100 and $400.
  • Maintenance tune-up: Around $100.


So although water heater leaks aren’t always an emergency, it’s best to take action right away to avoid any bigger problems. 

If you’re not comfortable taking on a few DIY projects, don’t let a leaky tank ruin your day! Get the help of a qualified professional to help find and fix the problem.

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