How to Fix Water Heater Leak in Water Heaters

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

Why Water Heater Leaks?

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

Eventually every heater leaks after some time, unless they are maintained properly or made of the plastic such as Rheem Marathon models. Leaking is one of the major reasons why the tank-type heater should not be installed in the area where the leak could damage the property.

Puddle of water as the symptom of the water heater leak

The most obvious sign of the water heater leak is the puddle of water underneath the WH. And there are several reasons why there is a puddle of water: leaking tank, leak from the plumbing fittings, TPR valve or condensation. Either the heater or the faucet is leaking the operating costs will increase or your will have an insufficient hot water.

Water leaking from the drain valve

Water is leaking on the drain valve when it is not closed tightly. Once you put the Teflon tape and closed the drain valve firmly the leak should stop. Otherwise, if the leak is persistent, the drain valve replacement is the only solution.


Condensation is usually considered as the water heater leak. Condensation usually takes place after the long draw of hot water or when the gas water heater is used for the first time. Modern, high efficient heater will condensate more than the old ones as they have cooler gases. So how to fix the condensation?

If there is a puddle under the WH, wipe the water, 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 to minimize the temperature drop during usage. Find more info here.

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TPR valve leak

Be aware that TPR valve is the safety device. If the temperature and pressure relief valve is leaking, or it is leaking from the discharge pipe, TPR valve might be releasing the build-up pressure inside the water tank. The excessive pressure in the tank causes joints, welds and gaskets to fail so adding the expansion tank will solve the problem. Check first where it is leaking. If it is leaking from the threaded connection you might have to tighten it up or put more Teflon tape. If the TPR valve is open you should check what the cause for its activation is.

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, for loose connections, tighten it.

Rusty tank leak

If there is a water heater leak due to the tank corrosion you might have to replace your old water heater. All metal tanks are protected with one or two anode rods, so during the time when the rod is depleted the corrosion will increase rapidly. Regular inspection of the anode rod and replacement if it is needed will make your WH tank last longer and eliminate potential leak problem.

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

There is another easy fix if small leaking such as dripping from the TPR valve or condensation occurs from time to time. A metal drain pan with the diameter at least 4" larger than the diameter of the WH and close to 2" in height should be installed. Keep in mind that condensation is sometimes considered as the water heater leak and depends on the season it will increase and decrease.

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