Water leaking under the kitchen sink: find it, then fix it

What to check first

1. Slip nuts on the drain

   Drips at the plastic joints of the P-trap usually mean a loose slip nut or a worn slip-joint washer. Hand-tighten the nut first, and replace the washer if it still drips.

2. The sink strainer

   Water running down the outside of the drain pipe from right under the sink comes from the basket strainer seal. Reseal it with plumber's putty or replace the strainer.

3. Supply lines and shutoff valves

   If it drips even when the faucet is off, check the supply lines and the valve stems. Old, kinked or bulging supply lines should be replaced.

4. Dishwasher and disposal connections

   Check the dishwasher drain hose clamp and the disposal's drain connections, if you have them.

5. The faucet

   Water pooling on top of the cabinet floor from above can come from the faucet base or the sprayer hose.

Parts you may need

• Slip-joint washers and nutsKitchen drains are usually 1-1/2 inch.
• P-trap kitOnly if the trap is cracked or corroded. Match the pipe size.
• Braided faucet supply linesCheck the length and both connections. The valve end is usually 3/8 inch compression.
• Basket strainer and plumber's puttyIf the leak is at the strainer.
• Hose clampFor a dishwasher drain hose connection.

Tools

• Flashlight
• Bucket and towels
• Channel-lock pliers
• Adjustable wrench