It’s a good idea to regularly check under your sink for water leaks. If your have a particularly cluttered cabinet water leaks may not be obvious. Remove the items under your sink and check for any moisture on the cabinet base.
If you find water under the cabinet you will need to determine where the water is leaking. Water may leak at the water cutoff valve, from beneath the trap or where the water supply lines feed into the faucet.
A close visual inspection should reveal the source of your leak. If it’s a particularly slow leak and not obvious where the water is coming from, you can place dry paper towels on the base of the cabinet. A water drip will reveal itself as a damp spot on the paper towel, leading you to the source of the water leak directly above.
How to fix a leak under the cabinet
If the leak is at the water cutoff valve or the supply line you should first try to tighten the connection where the line runs into the cutoff valve or to the kitchen faucet. Use an adjustable wrench to turn the nut attached to the supply line a quarter turn. Often this is all that is needed to fix the leak. Do not over-tighten the nut. Just a little pressure is all that is needed.
If the leaks persists you can try applying some plumbers grease or pipe compound to the treads of the supply line. You may also need to replace the supply line. You can buy a replacement at your local home-supply store. Be sure to turn of the water at the valve before replacing the line.
If the water is leaking from the trap under the sink you may have a leak that is backing water up into the pipe. If so, follow our instructions to unclog a sink drain.
If the leak is at the faucet, follow our instructions below for repairing faucet leaks:
- How to fix a compression faucet leak
- How to fix a ceramic disk faucet leak
- How to fix a rotary ball faucet leak
- How to fix a cartridge faucet leak