How to Fix a Sink Drain Leak
Updated February 25, 2026
Stop water leaking under the sink by tightening or replacing the drain basket, P-trap connections, or tailpiece -- the three most common leak points.
Overview
Water under the sink is coming from one of three places: the drain basket where it connects to the sink bowl, the slip-joint connections on the P-trap, or the tailpiece between them. Finding the exact leak point is the first step. Dry everything, run water, and watch. The fix is usually tightening a slip nut, replacing a worn washer, or resealing the drain basket with fresh plumber's putty. Most sink drain leaks cost nothing to fix -- just a wrench and 15 minutes.
What You'll Need
Safety First
- Place a bucket under the P-trap before loosening any connections. The trap holds water that drains when disconnected.
- If the leak is at the wall connection (where the drain enters the wall), be careful not to torque the pipe inside the wall. Old drain pipes can crack or separate at the wall fitting.
Step-by-Step Instructions
- Find the Exact Leak Point
Clear everything out from under the sink. Dry all the drain pipes and connections with a towel. Place a dry paper towel under each connection point: the drain basket (where the drain meets the sink bowl from below), the slip joints on the P-trap (the large plastic or chrome nuts), and the connection to the wall drain pipe. Run water in the sink for 2 minutes. Check the paper towels. The first one to get wet identifies the leak location.
Tip: If the leak only happens when the sink is full and draining (not during a trickle), the problem is likely at a slip joint that seals under low flow but fails under the pressure of a full drain. Fill the sink and release the stopper to test under full drain conditions. - Fix a Drain Basket Leak
The drain basket is the chrome or stainless piece visible in the sink bowl. It is sealed to the sink with plumber's putty from above and a rubber gasket and locknut from below. If water drips from the bottom of the drain basket: tighten the locknut (large nut directly under the sink around the drain body) with channel-lock pliers. If tightening does not stop it, the plumber's putty has dried out. Remove the locknut, push the basket up and out from below, scrape the old putty, roll a fresh rope of plumber's putty, press the basket back in, and retighten the locknut.
Tip: Plumber's putty stays pliable for years and creates a watertight seal between the drain flange and the sink surface. Silicone caulk works too but makes future removal harder. For stainless and porcelain sinks, putty is the standard. For granite composite or marble, use silicone -- putty can stain porous materials. - Fix a P-Trap Slip Joint Leak
P-trap connections use slip nuts with nylon or rubber washers inside. Hand-tighten the slip nut, then a quarter turn with channel-lock pliers. Over-tightening cracks plastic nuts. If the washer is compressed flat or cracked, replace it -- slip joint washers cost $1-$2 for a pack. Slide the slip nut back, slide the old washer off, slide the new washer on (tapered side facing the joint), slide the nut forward, and tighten. PVC P-traps: hand-tight plus a quarter turn. Chrome P-traps: slightly more torque, but still not heavy-handed.
Tip: If the P-trap itself is cracked or corroded (common on old chrome traps), replace the entire trap assembly. A PVC P-trap kit costs $5-$10 and includes the trap, tailpiece, washers, and nuts. Chrome replacement traps cost $15-$25. PVC is the modern standard and easier to work with. - Fix a Tailpiece Leak
The tailpiece is the straight vertical pipe between the drain basket and the P-trap. It connects to both with slip joints. If the leak is at the top (where the tailpiece meets the drain basket): tighten the slip nut. If the tailpiece is cracked or corroded, replace it -- $3-$5 for PVC, $8-$12 for chrome. Cut to length with a hacksaw if needed. Tailpieces come in 1-1/4 inch (bathroom) and 1-1/2 inch (kitchen) diameters.
Tip: If you have a garbage disposal, the tailpiece connects to the disposal outlet, not the drain basket. The disposal has its own gasket at the outlet. If the leak is at the disposal outlet, the gasket needs replacement -- a $3-$5 part specific to your disposal model.
Pro Tips
- Keep a small bag of assorted slip joint washers ($2-$3) under the sink. When a washer fails, you have the replacement immediately without a hardware store trip.
- Chrome P-traps look nicer than PVC on exposed plumbing (pedestal sinks, wall-mount sinks). But PVC is easier to work with, cheaper, and does not corrode. For sinks with a vanity cabinet hiding the plumbing, always use PVC.
- A persistent leak at the drain basket after re-puttying usually means the sink surface is not flat around the drain hole. Sand the area lightly with fine sandpaper to create a smooth bonding surface for the putty.
- If the drain pipes under the sink are a tangled mess of old chrome, plastic adapters, and mismatched fittings, replace the entire assembly. A PVC P-trap kit ($5-$10) with a new tailpiece ($3-$5) gives you clean, leak-free connections for $8-$15 total.
- Thread sealant tape (Teflon tape) is not needed on slip joint connections. The rubber or nylon washer creates the seal. Tape on slip joints can actually prevent the washer from seating properly.
When to Call a Pro
Call a plumber if the leak is inside the wall (pipe behind the wall is cracked or has a failed joint), if the sink drain connects to an old cast iron or galvanized drain pipe that crumbles when you touch it, or if the garbage disposal is leaking from the bottom (internal seal failure -- disposal needs replacement).
Frequently Asked Questions
When should I call a plumber to fix a sink drain leak?
Call a plumber if the leak is inside the wall (pipe behind the wall is cracked or has a failed joint), if the sink drain connects to an old cast iron or galvanized drain pipe that crumbles when you touch it, or if the garbage disposal is leaking from the bottom (internal seal failure -- disposal needs replacement).
What are some expert tips to fix a sink drain leak?
Keep a small bag of assorted slip joint washers ($2-$3) under the sink. When a washer fails, you have the replacement immediately without a hardware store trip. Chrome P-traps look nicer than PVC on exposed plumbing (pedestal sinks, wall-mount sinks). But PVC is easier to work with, cheaper, and does not corrode. For sinks with a vanity cabinet hiding the plumbing, always use PVC. A persistent leak at the drain basket after re-puttying usually means the sink surface is not flat around the drain hole. Sand the area lightly with fine sandpaper to create a smooth bonding surface for the putty. If the drain pipes under the sink are a tangled mess of old chrome, plastic adapters, and mismatched fittings, replace the entire assembly. A PVC P-trap kit ($5-$10) with a new tailpiece ($3-$5) gives you clean, leak-free connections for $8-$15 total. Thread sealant tape (Teflon tape) is not needed on slip joint connections. The rubber or nylon washer creates the seal. Tape on slip joints can actually prevent the washer from seating properly.
What tools do I need to fix a sink drain leak?
You will need: Channel-lock pliers or adjustable wrench (for slip nuts and locknuts), Plumber's putty (for drain basket resealing), Replacement slip joint washers ($1-$2 for an assorted pack), Bucket (to catch water when disconnecting the P-trap), Paper towels (for leak detection), Flashlight (for seeing under the sink).
When should I call a professional instead of doing this myself?
Call a plumber if the leak is inside the wall (pipe behind the wall is cracked or has a failed joint), if the sink drain connects to an old cast iron or galvanized drain pipe that crumbles when you touch it, or if the garbage disposal is leaking from the bottom (internal seal failure -- disposal needs replacement).
How difficult is this project?
This project is rated easy. Most homeowners with basic tools can complete it.
How long does this take?
Plan for approximately 15 - 45 minutes. First-timers may need extra time.
How much will this cost?
The estimated cost is $0 - $20. Costs vary by location and materials chosen.