Opening up the undersink cabinet to find damp, or even worse, rotting wood is no fun. Chances are you already suspect the sink plumbing as the cause of the problem, but you wills still need to pinpoint the exact issue. The following are three reasons your cabinet could be wet, which can help you narrow down your search for the exact leak.

#1: A leaking faucet

A common cause of a leak under the sink is actually the faucet above. Every faucet has O-rings and washers inside the handles. If these wear out, water begins to leak around the base of the handle, where it can run down through the fixture and under the sink. Replacing these O-rings and washers solves the issue. In some cases, the cause is not the faucet but the spray nozzle. In sinks equipped with a spray nozzle on a hose, a leak around the base of the nozzle causes water to run down the hose and under the sink. Simply replacing the washer located inside the nozzle where the hose screws into place stops the leak. The final issue with a faucet that can lead to wet beneath the sink is if the faucet assembly isn't seated correctly. In this case, tightening the bolts or replacing the seal around the base of the faucet assembly may be required.

#2: Pipe leaks

The most common cause of a leak under the sink will be from the undersink pipes. Place a bucket beneath the pipes to catch the dribble, then allow water to run down the drain to see if you can pinpoint the leak. Often, you will find that it comes from a joint where two pipes are connected. You can often remove the pipe, wrap the threads of the join with plumbers tape, then screw them back together to solve the problem. Sometimes the issue is a clog, which is causing water to sit in a weak spot for longer than necessary as the pipes drains slowly. In this case, removing the pipe and flushing out any clogging residue may be all that is required.

#3: Condensation issues

An often overlooked cause of a damp undersink area is condensation on your pipes. This is easy to spot since you will see the pipes coated in condensation after running the water. Generally, condensation occurs in cold weather when hot water is drained through the pipes, or in hot weather when cold water is drained. There are two ways to address this. The first is to leave the cabinet door open so air circulates and the temperature inside the cabinet equalizes. A more permanent fix is to wrap the pipes in a pipe insulating blanket.

For more help, contact a plumbing company like AAA Home Services in your area.