A leak in a copper water pipe behind a wall can cause damage to walls, ceilings and floors. Hidden moisture also increases the risk of dangerous mold buildup. A leak in a pipe behind a wall may start slowly and go undetected for a long time. Once a leak is found, it should be repaired as quickly as possible to limit the amount of damage done. There are a few ways to find a leak in a copper water pipe behind a wall, including the use of technological devices.
Turn off the power to any electrical circuits in the affected area of a water leak by switching off the appropriate breaker(s) at the home's service panel (breaker box).
Find any wet spots on the wall or water on the floor. Make a cut about 1 foot higher than the wet spot, using a drywall saw or a utility knife. Be careful not to cut too deeply, to prevent damaging pipes inside the wall. Also make sure there is no wiring in any wall cavities where you make cuts. Cut harder wall materials -- such as plaster -- with a reciprocating saw. Cut along studs, if possible, after marking their locations with a stud finder. Alternatively, look for screw heads or seam lines to locate studs.
Look inside the wall, using a flashlight and compact mirror, if necessary. Eliminate areas without leaks. Look for a watery spray or mist and note the highest point from which water is dripping. Cut the wall open again if the source of the leak is not near the original cut. Several cuts may be required, particularly if there are multiple leaks. Contact a professional contractor, if necessary.
Listen at the wall in the vicinity of the suspected leak for a hissing or splashing sound, which may indicate a smaller leak. Alternatively, a louder sound of water running, as though a faucet is being used, indicates a larger split in the pipe. Pinpoint a close location to the source and cut open the wall to provide access to the damaged pipe.
Find a leak and hidden moisture in the wall by using thermal imaging, which looks at naturally emitted infrared radiation to detect broken pipes and other problem areas without requiring the wall to be opened. Contact a professional trained in the use of this technology, if necessary.