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How To Repair Water Damage From A Leaking Water Heater

Note: This post may contain affiliate links. This means that at no cost to you, we may receive a small commission for made purchases.

An automatic shut-off valve is excellent insurance to have in any situation, especially when the water heater unit is located inside the home. Damage from water leaking out of your water heater is imminent unless fixed quickly, and the costs go up the longer the problem goes uncorrected. The culprit may have been something as simple as a pressure relief valve needing replacing or something catastrophic like a tank failure.

Here’s what you need to do to repair water damage in various places as well as how to get rid of mold and mildew caused by the water damage.

WARNING:  Mold can be extremely toxic and anytime you're dealing with more than a very small area, you will want to contact an expert on mold removal to address the situation.

Removing Mold and Mildew

water-damage-moldThe most common form of damage, especially if the leaking water heater isn’t repaired in a timely manner, is mold and mildew. Mold can be particularly dangerous to certain individuals and should be treated quickly.

You can often treat small areas yourself by making a mixture of 1 cup bleach to 7 cups water to kill mold and mildew. Put the mixture in a spray bottle and lightly cover the affected area. wet a sponge or rag with the mixture and use it to wash the mess away. Wipe the area with clean water to remove residue. Repeat as necessary.

For long-term mold build-up, the process may need to be repeated. When complete, paint the area to reduce future growth.

Related: Mold Remediation – How to Remove Mold

Baseboards and Trim

Soft woodwork such as base board or corner trim is easily ruined by prolonged contact with water.

To remove damaged trim, carefully cut along the edges of the damaged piece with a sharp utility knife to break the paint seal. Use a putty knife or wide screwdriver to carefully pry the piece out from the wall until you can grip it with your hand. Start at one end of the piece and work towards the other, pulling each nail out slowly to avoid causing additional damage.

Paint or stain the replacement trim and allow it to dry before putting it in place.

Wood Floors

water-damage-wood-floorWater will cause discoloration in wood flooring and may lead to warping if the floor remains saturated for an extended period of time.

In some cases, stains can be removed by using a wax stripping solution and rewaxing the floor. It may even be necessary to sand the floor and apply a new polyurethane finish.

In more advanced cases of a water damaged floor (ie: major leak or radiant floor heating leak), repairing the subfloor may even be necessary. For best results, refinish the entire room, as trying to repair a small area will be visible for many years, providing an obvious indication that the floor has had some form of damage.


In most situations, you can save the carpet if you act soon enough.

A shop vac is usually sufficient, as long as it is rated for fluids, but you can also rent a carpet cleaner at most hardware and grocery stores. When you’re not able to vacuum any more water out of the carpet, place one or more fans (or better yet, a good air mover) so that you can cover the entire area with moving air, using the highest speed setting.

Cool dry air is useful in drying a carpet, so turn your air conditioner to a cool temperature and leave it running overnight. If you have a carpet cleaner, use it in the normal fashion after the carpet has been dried. For tough stains, use a scrub brush dipped in the bleach mixture described above before cleaning.

Drywall Repair

For small area of drywall damage, you can make repairs using a patch. Carefully cut out the damaged area, making sure that both side cuts are centered over a stud. If necessary, make the hole larger to accomplish this.

Toenail a horizontal 2×4 between the studs at the top of the hole, centered between the existing drywall and the newly cut opening. If the opening spans more than one stud, you will need to use multiple pieces of 2×4 as well. These pieces are used to keep the old and new drywall flush and to give you an easy way of fastening the patch in place.

Place the replacement piece in the opening and insert drywall screws every 8 inches around the opening. Using a putty knife, apply drywall compound around the edges and allow them to dry. Dampen a stiff sponge and carefully wipe the excess drywall compound off. For best results, repaint the entire room.

Plaster Repair

Small areas of damaged plaster can be drilled out and patched using spackling, but larger areas will require more intensive patching.

Using a rotary tool or grinder, cut the damaged plaster out. The cut will be very shallow, usually around 1/2 inch, and cutting deeper could damage the underlying lath. Set a fan to blow into the opening and leave it running until the interior of the wall has dried. Replaster the affected area and allow it to dry.

Note: If you are repairing a wall that has been saturated, it may be necessary to make a larger opening and replace any wet insulation before you close up the wall. Always make sure the interior of the wall is dry before you seal it, or mold and mildew may become a problem later.


Something not often mentioned with water heater leaks is that they are an invitation for all sorts of pests to move into, under, or around your home. Whether it’s mice, rats, cockroaches, raccoons, or even wolf spiders, these critters love to have a constant source of water and shelter.

author avatar
Anthony Barnes
Anthony Barnes is the founder of Water Heater Hub and a second-generation plumber by profession. Before developing Water Heater Hub, Anthony Barnes was a full-time plumber, and he has undertaken a wide variety of projects over the decades. As a second-generation plumber, it was easy for Anthony to get used to the technicalities of all from a tender age


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