Water usually leaks under a sink because of loose drain connections, a worn or cracked supply line, a shutoff valve that is failing, a faucet that leaks from its base, or a dishwasher or garbage disposal connection. Figuring out whether the leak happens all the time or only when the sink is used can narrow it down.
Leaks Only When the Sink Drains
If water drips only while the sink is draining, the problem is likely in the drain pipes. The curved trap under the sink has slip nuts that can loosen over time. The washer inside them can also wear out. Hand-tightening a loose nut sometimes stops the drip, but do not overtighten plastic fittings.
Leaks All the Time
If water drips even when the sink is not in use, a supply line or valve is more likely. The flexible supply lines that connect the faucet to the shutoff valves can crack with age. The valves themselves can leak around the stem or handle. These are under constant pressure, so they can get worse quickly.
Faucet and Appliance Leaks
Water that runs down from the faucet base, or pools near the back of the cabinet, may come from a worn faucet seal. In kitchens, the dishwasher drain hose and the garbage disposal can leak at their connections or seals.
How to Check
Dry everything under the sink with a towel. Put a dry paper towel on the cabinet floor, then run water in the sink. Watch where new drops appear first. Check the cabinet floor for soft spots or swelling, since slow leaks can damage the wood over time.
If you cannot stop the leak or the cabinet is damaged, close the shutoff valves and have the leak traced and repaired. Under-sink leaks are a common, quick fix during routine kitchen and bath plumbing service. Call JPR Plumbing at (833) 603-1840.