How to Trace a Plumbing Water Leak

Tracing a leak in your home’s plumbing can be tricky, but it is necessary to avoid the potential damage that leaking pipes can cause. Finding the source of the leak depends largely on the type of leak you have. A leaking pipe under your sink is easier to find than one that is blocked by ceilings or walls. The first step to tracing the leaking pipe is to determine that you do indeed have a leak, and then you must inspect each room of your home.

Confirm the Leak

Move appliances out of their location wherever possible to look for the source of the moisture. A damaged supply line on a dishwasher, for example, will leak water around the appliance. If this does not reveal the source of moisture, turn off every faucet, appliance and fixture in your home that uses water, and mark where the needle is pointing on your water meter with a pencil or a piece of tape. Leave fixtures, faucets and appliances off for about eight hours, and read the meter again. If the needle has moved, this indicates a leak somewhere in your plumbing system.

Kitchens and Bathrooms

Open cabinet doors beneath sinks and shine a flashlight inside to look for moisture at joints and at the bottom of the P trap. Signs of a leaking pipe may also include corrosion on the supply line fittings and valves. Clear out the cabinet and examine the bottom for water stains, dampness, mold or mildew, and buckled or peeling material, which indicates a leak has occurred. Tighten fittings and wipe away moisture. Turn the water back on to see if this fixes the problem. Sometimes the leak is in the supply valve or line, and it will be evident when the supply is turned off and then activated again. If this is the problem, replace the leaking supply line. You can do the same for all water-using fixtures and appliances such as your toilet, dishwasher and refrigerator.

Floors, Walls, and Ceilings

Examine the flooring around fixtures and appliances that use water, including toilets, bathtubs, dishwashers, and refrigerators. Cracked or warped flooring or spongy spots in the floor indicate the presence of moisture and a possible leak. Examine the walls and ceilings in rooms located directly beneath bathrooms as well. Stains on the ceiling or walls, and bubbling or peeling paint or wallpaper, indicate a leak somewhere in those pipes. Contact a plumber to inspect and repair the leak, and to confirm its location before you begin ripping out walls or floors.

Basements and Crawlspaces

Inspect exposed pipes in basements and crawlspaces. Corrosion or moisture present around the pipes indicates a leak. If you see mold, mildew or rotted wood around these pipes, your leak is probably in this area. Water tends to travel downward, and often the location of water stains is not the exact location of the leaking pipe. Still, it is a good indicator of the general area of the source of moisture.