How to Fix a Water Heater Leak
Troubleshooting Tips

Plumbing wrenchesImage source: Pixabay

Gas and electric water heater leak repair guide. A detailed explanation of the leaking problem, common causes, and tips on troubleshooting leaky heater from the bottom, from the top, and the drain valve.

Why do water heaters leak?

Almost all gas and electric water heaters that are made of steel are exposed to corrosive water action.

So, every heater could develop a leak after some time, especially if it is old unless they are correctly maintained or made of plastic such as Rheem Marathon models. Leaking is one of the primary reasons why tank-type heaters should not be installed in the area where the leakage could damage the property, such as in the attic.

Determine the source of the leak

There are many reasons why a water heater leaks, and some are explained below. It is essential to find the source as soon as possible. Even if you see a small puddle of water. Inspect the area and try to determine the cause. If it is hard to figure out where it is coming from, dry the area, put some kitchen towels where you first noticed the water, and wait. The wet area might reveal the source.

If it is hard to determine the source, immediately contact a plumber to help you, to avoid costly repairs.

Using a water meter to check for leaks

A water meter is a device that keeps track of how much water is used in your home. It is usually located in the basement or outside, in front or side of the house.

You can check for water leaks no matter which type of a water meter is used, as long as it measures your house water consumption individually.

In order to see if there is a water leak in your house, first close all the taps and devices, so no water is being used on your property.

Identify, memorize or mark a location of the water meter dial hand. Do not run water for 20-30 minutes. If the dial has moved, there is a leak in your home.

Before you spend most of your day trying to find the problem, check out the most common reasons for a leak and tips on how to repair it.

If a leak is bad, find the main shut-off valve as soon as possible and close it. The valve is usually located in the crawl space, basement, and where the water supply enters your home.

If you have found a leak, you can also close the shut-off valve installed for that fixture or device.

Puddle of water as the symptom of the water heater leak

The most obvious sign of a water heater leak is the puddle of water underneath the unit. So there are several reasons why there is a puddle of water: a leak from the tank, plumbing fittings, TPR valve, or condensation. Wherever the problems are coming from, the operating costs will increase, or you won't have enough hot water for a shower.

Water leaking from the drain valve

Water is leaking on the drain valve when the part is not closed tightly, or there is a crack in the element, especially if it is made from plastic.

Remove the faulty valve or install a new one, but the Teflon tape around the threads, and after you tighten it firmly, the dripping should stop. If the problem is still there, the drain valve must be replaced.


Condensation is usually considered a water heater leak. Condensation usually occurs after the long draw of hot water or when the gas water heater is used for the first time. Modern, high efficient heaters will condensate more than the old ones as the temperature of products of combustion is lower.

So how to fix the condensation?

If there is a puddle under the heater, wipe it up, turn the unit ON and wait for several hours. After the water temperature is above 110-115 F, condensation should stop. Install the water heater with the capacity that will minimize the temperature drop during usage.

- Find Plumbers In Your Area -

TPR valve leak

Be aware that the TPR valve is the safety device. If the temperature and pressure relief valve is leaking or coming from the discharge pipe, a TPR valve might release the build-up pressure inside the water tank. Excessive pressure in the tank causes joints, welds, and gaskets to fail, so adding the expansion tank will solve the problem. If the TPR goes bad and it doesn't open when the pressure is high, the tank might eventually burst.

First, check where it is leaking from. If the problem is with the threaded connection, you might have to tighten it up or put more Teflon tape on its threads. If the TPR valve is opened, you should check the cause of its activation.

Ensure that the thermostat's temperature is not set too high (keep it around 125 F) and test the valve at least twice a year.

If you see that the heater started to deform, immediately contact a plumber.

Leaking from the piping fittings, gas valve or electric elements

Check all the connections and fittings for possible leaks, both inlet and outlet sides. Remove the fittings or valves, re-apply pipe joint compound or Teflon tape, replace damaged gaskets or check for threads. Whatever is damaged, replace it, and tighten and the loose connections.

Is your plumbing leaking? Find out more about leak symptoms, common causes and how to fix them.

Rusty tank leak

If there is a water heater leak due to tank corrosion, you might have to replace your old water heater. This is how. All metal tanks are protected with one or two anode rods, so when the rod is depleted the corrosion increases rapidly.

If the rust is corroding the tank, you will often see hot water at the tap brown or rusty color. This is a sign to consider replacing the water heater to prevent damages due to leaking.

Regular inspection of the anode rod and replacement, if it is needed, will make your tank last longer and eliminate the potential problem.

Sediment build-up

Sediment build-up at the bottom of the water heater creates a layer that insulates the water inside the tank from the gas burner and heat, so the heater will run longer, overheat, deteriorate and eventually rupture.

Popping noise, lower performance and efficiency, and lukewarm water are some of the signs that there is a sediment build-up inside the heater.

To reduce the risk, it is recommended to flush and drain the tank at least once a year.

Contaminated air

Contaminated air is another reason for the rust and leaky water heater. When the air is polluted with all kinds of household chemical vapors and dust, and when they come in contact with the flame or electrical connection, various acids will form and attack the metal tank.

Could a drain pan help?

To protect the surrounding from water, installing a drain pan is a good idea, especially when installing a new water heater. A metal drain pan with a diameter of at least 4" larger than the diameter of the heater and close to 2" in height is recommended. Keep in mind that condensation is sometimes considered the water heater leak, and depends on the season, it will increase and decrease.


It is essential to understand that a leaky water heater could, from a minor issue, lead to a big problem. When a leak develops, there is a slow leak so that water won't rush out at once. It may go unnoticed for days or weeks. Then, as the problem becomes more significant, it will not only affect the heating operation but will cause flooding, damage the property and make a severe impact on your wallet.

A leaking water heater can also be a health-related problem, as the wet area is a fertile ground for mold and mildew growth. This is why it is crucial to contact a professional for repairs and proper regular inspection and maintenance before the problem occurs.

Find Trusted Plumbers & Get Free Quotes


Leave a Comment

[ ? ]

Author Information (optional)

Submit Your Contribution

  •  submission guidelines.

(You can preview and edit on the next page)