How to Fix a Leaking Kitchen Sink Drain

A dripping kitchen sink drain is one of those problems that feels urgent but almost never is. Water pooling under your sink will eventually damage your cabinet, but you have time to do this right. The good news: you're looking at a 20-minute fix with tools you probably own. Kitchen sink drains are simple systems—just a basin, some pipe, and compression fittings that hold it together. When they leak, it's almost always because something came loose or a rubber washer compressed and lost its seal. This guide walks you through finding the leak, tightening what matters, and replacing parts only if you have to. You don't need a plumber for this. You don't need special skills. You do need to get comfortable working upside-down under a cabinet with your head in a dark space, but the actual work is straightforward. Start with what you can see and feel, work methodically through the connections, and test after each tightening. Most of the time, you'll solve it without turning a single part.

1. Find the Leak First. Remove everything from under the sink—cleaning supplies, bags, old bottles. Wipe the pipes and connections completely dry with a towel. Run water at the sink for 10 seconds while watching underneath, or place a dry paper towel near each joint to see where water appears first. The leak will be visible immediately once you know where to look.
2. Tighten the Trap Nuts. The trap is the U-shaped piece of pipe directly below the sink. It has two slip nuts—one connecting to the sink basin above, one connecting to the wall drain below. Place one hand on the threaded pipe fitting to hold it steady, then grip the slip nut with your other hand and turn it clockwise. Go hand-tight only—you want resistance, not a wrestling match.
3. Diagnose the Washer. If hand-tightening didn't stop the leak, use a pipe wrench to turn the nut one more quarter-turn. If water still drips from that same connection after a full minute of running water, you likely have a bad washer. Loosen the slip nut again and catch the water that spills into a bucket. Look inside the nut—you'll see a rubber or nylon washer sitting in a threaded cone. If it's visibly cracked, deformed, or hard, it needs replacing.
4. Swap in New Washers. Remove the slip nut completely. The washer will fall into your hand or the bucket below. Buy identical replacement washers at the hardware store (bring the old one or the nut itself to match). Drop the new washer into the nut and reinstall it hand-tight, then use the wrench for a quarter-turn more. Some leaks also come from a cone-shaped gasket that sits above the washer—if you see a plastic or rubber cone that looks deformed, replace that too.
5. Secure the Basin Connection. Above the trap, where the drain outlet from the sink basin meets the vertical pipe, there's another slip nut. This one also loosens with age and vibration from running water. Hand-tighten it, then add a quarter-turn with your wrench. This connection causes leaks just as often as the trap connections do, but people often miss it because it's less visible.
6. Verify the Fix Works. Turn the sink on at normal flow and let it run. Watch all three connection points—where the basin meets the tailpiece, where the tailpiece meets the trap, and where the trap meets the wall drain. Dry any water you see accumulate on the exterior of the pipes. If no new water beads up on the connection joints themselves within 60 seconds, you're done.
7. Diagnose Deeper Issues. If water still drips from the same spot after you've tightened and replaced washers, the problem is likely a cracked section of pipe or deteriorated putty seal around the sink drain opening. A crack in the actual PVC pipe means that section needs replacement, which requires unbolting the sink or cutting the pipe. If the leak is at the very top of the drain opening where it meets the sink basin, old plumber's putty has probably failed and needs to be resealed or caulked.