How to Replace a Leaking P-Trap Under Your Kitchen Sink

A leaking P-trap is one of those problems that looks scarier than it is. The P-trap is the U-shaped pipe under your sink that holds standing water to create a seal against sewer gases. When it leaks, water pools under the cabinet, which means you have to act fast before it damages the cabinet floor or the items stored below. The good news: this is one of the most straightforward plumbing fixes a homeowner can do. You don't need special skills or expensive tools, and the part itself costs less than thirty dollars. The real win is knowing that what feels like a plumbing emergency is actually just a matter of unbolting a pipe and bolting on a new one. Done right, your new trap will last years without issue.

1. Kill the Water First. Locate the shut-off valve under the sink (usually a small chrome knob on the supply line coming from the wall or floor). Turn it clockwise until it stops. Run water at the sink for a few seconds to confirm the supply is off. If you can't find a shut-off valve under the sink, you'll need to shut off the main water supply to the house.
2. Catch the Spillage. Place a bucket or shallow pan directly under the U-shaped section of the trap. The trap contains standing water that will pour out the moment you loosen the first fitting. Set the bucket so it catches water from both the horizontal and vertical sections.
3. Loosen Both Nuts. The P-trap connects to the sink drain above it and to the wall drain below it via two large hexagonal nuts called slip nuts. The top nut secures the tailpiece (the pipe coming down from the sink) to the trap. The bottom nut secures the trap to the drain line going into the wall. Using an adjustable wrench, grip the slip nut and turn it counterclockwise. Go hand-tight first, then give it a quarter turn more with the wrench to break it loose. Don't turn it all the way off yet—just break the seal.
4. Free the Top Connection. Now unscrew the top slip nut completely by hand. When you remove it, you'll see a rubber washer or beveled ring inside the fitting. Keep this washer—you'll need it or replace it with the new trap's washer. Set both the nut and washer aside in a safe spot.
5. Pull the Trap Down. With the top nut and washer removed, gently pull the P-trap downward and away from the sink tailpiece. The trap may be stuck slightly—don't force it. If it won't budge, use a pipe wrench with a gentle rocking motion to work it free. Once separated, water will drain into your bucket.
6. Free the Wall Connection. Now unscrew the bottom slip nut that connects the trap to the drain line going into the wall. Again, turn it hand-tight first, then finish with the wrench. Remove the nut completely and set it aside with the others. Carefully pull the trap straight down and away from the wall drain. Water still in the trap will drip out—that's normal.
7. Clean All Threads. Before you install the new trap, wipe down the threads and connection points on both the sink tailpiece and the wall drain line with a dry rag. Remove any debris, old rubber, or corrosion. This ensures a tight seal with your new trap. If the tailpiece or wall drain has visible corrosion or damage, make a note—you may need to replace those separately.
8. Test the Fit First. Take the new P-trap out of the box and dry-fit it first. Slide the top of the trap up to meet the sink tailpiece and the bottom outlet toward the wall drain. The trap should align without forcing. Check that the U-bend is vertical (not tilted), and the outlets point straight into their connections. Make small adjustments to the position of the sink tailpiece if needed.
9. Seal the Top First. Slide the new washer (or the old one if it's in good shape) onto the sink tailpiece, then slide the slip nut up and thread it by hand into the fitting on top of the trap. Hand-tighten it until it's snug. Once hand-tight, use an adjustable wrench to turn it an additional quarter turn clockwise. Don't over-tighten—slip nuts are easy to crack if you bear down too hard.
10. Secure the Wall Connection. Slide the bottom slip nut and its washer onto the outlet of the trap, then thread it by hand into the wall drain fitting. Hand-tighten until snug, then finish with a quarter turn of the wrench. Like the top, snug is the goal—not crushing force.
11. Run the Water Test. Turn the shut-off valve counterclockwise to restore water pressure. Run water from the sink for 30 seconds at a steady flow. Watch the trap and both connection points closely for drips or streams. Leave the bucket underneath and wait five minutes, then check again. A single drop or two is not uncommon in the first minute, but steady dripping means you need to tighten the fitting more.
12. Verify the Seal. If tightening doesn't stop the leak, turn off the water again and loosen the leaking fitting by a quarter turn. Check that the washer is seated properly and not twisted. Tighten again and retest. If the leak persists after two attempts, you may have a cracked fitting or a defective washer. Replace the washer first; if that doesn't work, the trap itself may be defective and needs replacement.