Troubleshooting a Faucet that Leaks Water under the Sink

man with a wrench on a pipe

A leaking faucet under the sink can be complicated to fix. If you’re facing a faucet leak that originates at the faucet setup itself, you can easily replace the washers inside the faucet and fix the problem. A leak under the sink, however, requires attention to the pipes under the sink. Fixing the problem resembles the steps you would need to fix a clogged drain.

Type of Pipes

Regardless of the type of pipes your sink has under it (PVC or Metal), piping systems will not be very different from each other. There will be a straight pipe coming outside from the side, a straight pipe coming out from the wall behind the sink and a P-trap connecting the two pipes.

Step 1 - Gather Supplies

man working on pipes below a sink

You will usually need only adjustable pliers and some Teflon tape to repair a faucet leak under the sink. You can also purchase a PVC kit that comes very cheap for repairs. It will include new washers, slipnuts, etc. All of these can be replaced to repair an under-the-sink faucet leak.

Step 2 - Turn off Water Supply

Before you start your project, it is imperative that you shut off the water supply for an easier and cleaner job. You can locate a shut-off valve under the sink and tighten it with your hand. If it is not under the sink, you may have to access the main water supply valve and turn it off.

Step 3 - Remove Old Drain Pipes

You can start removing the old drain pipes by first loosening the nut that connects the drain pipe to the bottom of the sink. Use adjustable pliers to start doing this as the fit will be very tight. Once you have loosened the nut, you can unscrew it with your hand. Make sure you’re holding the entire pipe assembly by hand though during unscrewing of the nut.

If you do not, the whole assembly may fall and spill all its contents like washers etc. and you will have to spend more time organizing it all. Keep a bucket below the pipes under the sink always. When you’re loosening the nuts, some water that is in the pipelines may fall onto the floor. You can prevent any mess by collecting it all into a bucket underneath.

Step 4 - Size Up your New Pipes

man taking a measurement below a sink

When you are done loosening and removing your pipes for repairing an under the sink faucet leak, measure the pipes! You will need this measurement to cut the new pipes in your PVC kit to length. You can do that easily by using a simple hacksaw. Once you have cut them to size, connect the whole assembly exactly like how the old assembly was. Make sure you apply Teflon tape to the pipe threads to prevent further leaks.

Step 5 - Evaluate

After you have done replacing and reattaching the whole assembly, turn on the water now. If you have a faucet and control for both cold and hot water, run both cold and hot water separately and check for faucet leaks under the sink. For added assurance that there are no leaks, place a bucket underneath the sink for a few days and use the tap like you normally would.