Repairing a Leaky Water Heater

May 21, 2010

Repairman working on water heaterHow do I fix a small leak in my hot water heater?

By Karen from Brooklyn, CT



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Best Answer

Water heaters are usually sealed-units; only leaky pipes and fittings can be repaired.
w1z111-C.R.H. Water heaters can develop leaks over time; but only a few of the reasons that one might leak are repairable. Other leaks mean the unit is ready for replacement.
Difficulty: Moderately Easy Instructions
Things You'll Need:
As noted

Step 1 Assessing your leaky water heater:

Water heaters are more or less "sealed-units". That is, the tank itself, usually lined with glass or other protective surface, is not repairable by DIY handy persons. In fact, rarely are water heaters that leak from the tank itself ever repaired. They are replaced, instead.


That said, look at your leaking water heater, to try to determine just where the leak is coming from. If you are sure it is not coming from the tank itself, then it must be coming from the piping and fittings attached to it. In that case, you can likely fix the leak.

Step 2

Be sure to check the pressure-relief valve, too. The only repairable kind of leaks:
If you determine that the leak is coming from one of the fittings or piping outside the tank itself, all you can really do to stop the leak is try tightening up on the fittings involved.

This article assumes that the leaking water heater is plumbed in with threaded fittings and piping. For water heaters plumbed in with copper tubing and sweat fittings, you might need to cut out and replace leaky fittings, if they cannot be re-soldered in place. See link below for helpful tips on Soldering Copper Tubing and Fittings.


Sometimes, water heater "pressure-relief" valves also go bad. That's the odd-looking fitting attached on the side of the water heater tank; and has a small handle on top for manual operation. If that device is leaking, it probably needs to be replaced. You will still have to drain the water heater some, so follow the steps below for shut-down and draining before you fiddle with the pressure-relief valve.

Step 3

Work safely!
Prep and drain:

Shut off power or gas:
If your water heater is electric, turn off the power at the circuit breaker. You should also lock it out and tag it with information that you are working on the circuit.

If your water heater is gas, turn off the gas feed. There is usually a small valve near the appliance; turn that valve one-quarter turn, so the arrow-marking on top is perpendicular to the pipe it is installed in.


Shut off the water: Turn off the cold water supply into the water heater, and the hot water out, by closing the in-line valves, usually located just above or beside the appliance.

Attach a garden hose to the sillcock valve at the bottom of the water heater, and run the hose to a floor drain or outside through a door. Open the sillcock to release pressure and drain some water out of the water heater.

Step 4 Disconnect the piping:

There should be unions attached to the piping going into and out of your water heater. Once you are certain the pressure is released from the appliance, disconnect the water in and water out by unscrewing the two unions. Catch any residual water released using a bucket.

Step 5 Fixing the leaks:

Now that your water heater is free-standing, you can work on the piping and fittings, to try tightening them up and/or re-sealing them.


Using a pipe wrench or other suitable wrench for the particular kind of fitting you wish to tighten, and holding any other fittings or sections of pipe with another pipe wrench; tighten up the subject fittings by turning them in a clockwise direction.

You might also need to take apart some of the fittings, to apply some Teflon tape or sealant on the threads.

Once you are comfortable that you have re-tightened the pipe and fittings you observed leaking, reassemble the setup, and reconnect the two unions.

Step 6 The test:

To test your leak-repairs, first close the lower drain-sillcock; then re-open the hot-water-out valve, then slowly re-open the cold-water-in valve. If you have sufficiently tightened and/or resealed the leaking fittings, you should see no more leaks.


Good luck.

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May 21, 2010

How do you fix a leaky water heater? Actually the information is for a friend in New Mexico who cannot afford a repair person. Thanks for any ideas.

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