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Water Heater Leaking From Top? Here’s What to Do

Troubleshooting from George Brazil

So your water heater is leaking from the top? Well, first off, relax. A leak at the top of your water heater is typically a much easier (and cheaper) fix than a leak at the bottom of your tank. But only if you find and fix the leak quickly!

So, what’s causing your water heater to leak water from the top? Well the most likely causes include:

  • The cold water inlet valve is leaking
  • A loose pipe fitting
  • A leaking temperature and pressure relief valve
  • A corroded anode rod
  • A leaking expansion tank
  • The tank itself is leaking

Let’s look at some of the steps you can take to determine which of these is your problem and how you can fix the leak.

Not interested in playing detective? Just contact us and we can locate and fix the leak in no time!

Step 1: Turn off the water heater

To be safe, turn off the gas or electricity to the water heater before you start tinkering with it.

Note: Turn off the water supply to the heater and dry the area as much as possible. You might need to let it sit for a while for water to seep out of small crevices around the connections. This will allow you to see the direction from which the water is coming when you turn the water back on. With slow leaks and standing water around the connections, you may not be able to see where the water is coming from. 

If you have a gas water heater, turn the gas valve to the OFF position. This valve is located on the water heater itself. You’ll also want to make sure that the ball valve on the gas piping connected to the heater is turned at a 90-degree angle (perpendicular to the piping).

Note: You will have to relight the pilot light once the leak is fixed and you are ready to use the water heater again. Follow the manufacturer’s lighting instructions in the owner’s manual (some models may have these instructions on the side of the water heater).

If you have an electric water heater, you’ll shut the power off at the electrical panel. Just look for a two-pole breaker labelled “water heater” and turn it to the OFF position.

Note: Before restoring power to an electric water heater, make sure that the tank is completely full of water. Otherwise, you can damage the heating elements inside the tank. The easiest way to do this is to turn the water valve on to the water heater then open the hot side of the bathtub valve and let it run full blast for a couple of minutes. This will remove any air within the water heater tank, eliminating any chance of damage to the heating elements.

Step 2: Find the leak

First, you’ll want to turn the water back on and watch carefully for where the water is coming from.

The most common leaky areas at the top of a water heater include:

  • Cold water inlet valve
  • Pipe fittings
  • T&P relief valve
  • The anode rod screw
  • The expansion tank
  • The tank itself

Use the pictures below to identify your leaky component then match it with the solution given in Step 3.

Cold water inlet valve

This valve delivers water to your water heater to be heated. If the valve sits directly over your heater and has gone bad, it will drip water onto the top of the tank.


Pipe fittings

Check all the connections on the top of the water heater. If any connection, such as the hot and cold water valves, is loose, it will leak water. Look for corroded parts (either in the form of rust buildup or a whitish powder substance or both) as this is a sign of leakage.


The T&P relief valve

Your water heater’s T&P relief valve (temperature and pressure relief valve), is a safety component that releases extremely hot water when your tank exceeds the preset temperature or pressure limits. Depending on your water heater model, this valve could be located on the side or the top of your water heater.

If your valve is located on the top of your water heater (like in the picture below), check to see where it’s leaking from. Two places it may be leaking from include:

  • From its base where it screws into the water heater
  • From the piping attached to the T&P relief valve and also coming out of the open end of the pipe


Anode rod port

Your anode rod is a long, thin rod that attracts all the corrosive elements in the water in order to prevent your water heater tank from corroding. But if the anode rod corrodes and isn’t replaced quickly, water will bubble up and leak through the port seen in the picture below.

The expansion tank is leaking

Many water heaters have an expansion tank installed on or over the top of them. This is a secondary safety device that absorbs excess hot water that occurs during the heating process.
This tank can leak from any of the following 3 areas:

  • The threaded connection
  • The expansion tank itself
  • The air valve on the opposite end of the threaded connection (water should never come out of this valve as it is supposed to be the “dry” side of the expansion tank that has only pressurized air in it)


The tank itself is leaking

If you notice that the water seems to be coming from the tank itself, there’s likely a tiny crack or hole in the top of the water heater. Unfortunately, that means the inner tank is corroding from the inside out and you’ll need to replace it as soon as possible. Often, if the tank is leaking, you’ll also see water bubbling up from the anode rod port.

Step 3: Repair or call a professional

Now that you’ve determined what’s leaking, let’s take a look at how to repair your leak.

  • If your cold water inlet valve is leaking, try tightening the nut that holds the handle in place. Use a wrench and turn the nut counter-clockwise. If the leak doesn’t stop, the valve itself may need to be replaced. Have a professional look at the valve to determine your best solution.
  • If a pipe fitting is loose and leaking water, you can try tightening the fitting with a wrench. But watch out for signs of corrosion. If the pipe is rusting, it may need to be replaced. If this is the case, you’ll need a professional to handle the job.
  • If your T&P relief valve is leaking from its base where it screws into the water heater, it needs to be replaced. If you’re attempting a DIY T&P relief valve replacement, follow these instructions. If there is water leaking from the piping attached to the T&P relief valve and also from the open end of the pipe, there’s most likely too much pressure in the water heater or the water is too hot. Have a professional inspect your tank to determine the issue.
  • If water is bubbling up and leaking from the anode rod port, you’ll need to call a professional immediately as this could mean your tank is about to burst. Why? Well, the bubbling water means that the anode rod has corroded and needs to be replaced. And once the anode rod rusts away, corrosive elements in the water will start eating away at the inner lining of your tank. Depending on how long your anode rod has corroded away, you may need to replace your water heater altogether.
  • If the expansion tank is leaking, verify the point of origin of the leak. If the source of the leak is the threaded connection, simply remove it from its connection point, apply some thread sealer and thread it back into place tightening it down firmly. If it’s leaking from any other point on the expansion tank, it will have to be replaced and this should be done by a professional as the pressure within the tank needs to be properly set in order for it to operate properly.
  • If the tank itself is leaking, you’ll need to call a professional to replace your tank immediately. The longer you wait to replace the tank, the higher the chance of the tank bursting and flooding your home.

Need help from a professional? Call an AZ plumber

If you need help repairing your water heater leak, we’re here to help.

Just contact us today and we’ll send over a qualified plumber.

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