Shut off the water and protect the area
- Turn off the hot and cold shut-off valves under the sink, usually by turning them clockwise. If they do not stop the flow, close the main water shut-off for the home.
- Clear out the cabinet and put down towels and a shallow pan or bucket.
- If a garbage disposal or other electrical device is near the water, turn it off and unplug it. If water has reached an outlet or wiring, do not touch it; shut off the circuit at the breaker only if you can do so safely without standing in water, and call an electrician or plumber.
A hidden leak can damage cabinets and flooring and encourage mold, so do not wait. If you suspect leaks elsewhere in the house too, signs of a leaking pipe lists what to look for.
Find where the water starts
Water travels along pipes before it drips, so the lowest wet spot is not necessarily the source.
- Dry all pipes, hoses, valves and the underside of the sink thoroughly.
- Reopen the shut-off valves and run the tap while watching with a flashlight. Look at the supply hoses, the valves, and the faucet base.
- Stop the drain, fill the basin partway, then release it. Watch the drain basket, the tailpiece and the trap.
- If you have a disposal or dishwasher, run them one at a time.
- Dry paper towels placed under each joint show the first wet spot clearly.
The timing helps: a leak when the sink is empty and the tap is off suggests supply lines or valves; a leak only while draining points to the drain side. For common kitchen causes, see why your kitchen sink is leaking from the bottom.
Fix: loose or worn slip joints
Slip nuts at the P-trap and tailpiece can loosen over time.
- Try hand-tightening the nut.
- If the leak continues, unscrew it, inspect the washer, and replace it if it is cracked, flattened or missing.
- Rebuild the joint with the washer’s bevel facing the correct way (it usually faces the direction of the connecting pipe) and tighten by hand, then a small additional turn with pliers if needed.
- Cracked pipe or fittings should be replaced.
Fix: sink drain flange (how to seal a sink drain)
If water drips from where the drain basket meets the sink or runs down the tailpiece, the flange seal may have failed.
- Place a bucket under the trap and disconnect the tailpiece and any trap parts.
- Loosen the locknut under the sink and remove the basket.
- Clean the old sealant from the sink opening.
- Apply new plumber’s putty or the sealant recommended by the sink or drain manufacturer, set the basket, and tighten the locknut from below.
- Wipe off excess squeeze-out, reassemble, and test.
Some drain kits use a rubber gasket instead of putty, and some sink materials need a specific sealant, so follow the instructions that came with your parts.
Fix: faucet supply hose
If the kitchen faucet hose is leaking, or the hose connections are damp:
- Close the shut-off valves and open the faucet to relieve pressure.
- Place a bucket underneath and unscrew the hose at the valve and at the faucet.
- Replace the hose with one of the right length and connection size. Bring the old one to the store to match it.
- Hand-tighten, snug slightly with a wrench, and avoid overtightening.
- Open the valves slowly and check for drips for several minutes.
Braided hoses that are corroded, bulging or old are better replaced than patched.
Fix: shut-off valve
A valve that drips from the stem or the connections may sometimes be tightened slightly at the packing nut, but older valves often fail when disturbed. If a valve will not close or keeps leaking, replacing it may require shutting off the main water supply and, depending on the pipe material, soldering or special fittings. That is a good point to call a plumber.
Temporary fixes
Epoxy putty or a repair clamp can slow a leak on a non-pressurized drain pipe for a short time, but they are not permanent repairs. Do not rely on tape or putty on supply lines or fittings under pressure. Plan a proper repair.
What does it cost?
Costs vary by area and by the part that failed. A washer, hose or valve is generally inexpensive in parts, while a plumber’s visit adds labor and often a minimum service fee. Larger repairs, such as replacing a faucet, disposal, or sink, cost more. Ask for a written estimate.
Hidden damage: cabinet and mold
After fixing the leak, dry the cabinet completely and look for soft or swollen wood and mold. A fan can speed drying. If you see widespread mold or the floor beneath is soft, a professional assessment is a sensible next step.
When to call a plumber
- You cannot identify the source, or the drip returns after the repair
- A shut-off valve will not close
- The leak is on a pressurized line and you cannot stop it
- The disposal or electrical equipment is wet
- You see rot, mold, or a spreading wet area
- Corroded or threaded metal pipe will not come apart
If the leak involves the disposal, go to garbage disposal leaking from the bottom. For an overview of other problems, see kitchen sink plumbing problems.