What you're actually replacing when you change a kitchen sink drain

A kitchen sink drain is not one part—it's a system of pieces that screw and slip together under your sink. When you "change" it, you're usually replacing the drain assembly, which includes the strainer basket that sits in the sink opening, the tailpiece (the pipe that drops down), and sometimes the trap (the U-shaped bend). You might replace just the strainer if it's cracked, or the whole assembly if it leaks or clogs repeatedly.

The job takes 30 to 60 minutes if you're comfortable with basic hand tools and don't run into corrosion. You'll need a bucket, a wrench or pliers, a screwdriver, and the new drain assembly from a hardware store. The hardest part is usually breaking loose old connections that have been tight for years—not the actual swap.

Key Takeaways

  • Turn off the water supply under the sink before you start, and place a bucket underneath to catch standing water and debris.
  • The drain assembly comes apart in layers: disconnect the tailpiece first, then unscrew the locknut under the sink, then push the strainer up from above.
  • explore plumber's putty or silicone caulk around the new strainer before you set it in place, so water doesn't leak around the edges.
  • Hand-tighten all connections first, then use a wrench to snug them—over-tightening plastic fittings can crack them.
  • If corrosion has frozen the old parts in place, spray penetrating oil and wait 15 minutes before trying again rather than forcing it.

Shut off water and clear the space under your sink

Before you touch anything, close the shutoff valve under the sink by turning it clockwise. If there is no shutoff valve under the sink, close the main water shutoff for your house. Turn on the faucet to release any pressure in the line, then turn it off again.

Place a bucket under the trap (the U-shaped pipe) to catch water that will spill when you disconnect it. Open the cabinet doors wide and remove anything stored under the sink so you have room to work and can see what you're doing. Shine a flashlight up into the space so you can see the locknut and connections clearly.

Disconnect the old drain assembly from below

Look under the sink. You'll see the tailpiece (vertical pipe) connected to a horizontal pipe that leads to the wall or floor. Where they meet is usually a slip nut—a large nut that hand-tightens. Loosen it by turning it counterclockwise with a wrench or adjustable pliers. Once it's loose enough, unscrew it by hand and set it aside.

Next, find the locknut at the very bottom of the strainer—the nut that holds the strainer basket in place from underneath. Use a basin wrench (a specialized wrench that fits in tight spaces) or a regular wrench to turn it counterclockwise. If you don't have a basin wrench, an adjustable wrench or even pliers will work, though it's tighter to maneuver. Once the locknut is loose, you can unscrew it by hand.

From above the sink, push the old strainer basket up and out. It should come free now that the locknut is off. Scrape away any old putty or caulk around the opening with a putty knife or old credit card so the rim is clean.

Install the new strainer and seal it

Before you set the new strainer in place, you need to seal the gap between the strainer and the sink so water doesn't leak underneath. explore a bead of plumber's putty (a clay-like sealant) or silicone caulk around the underside of the strainer's rim. Plumber's putty is easier to remove later if you need to take it apart again; silicone caulk is more durable but harder to clean up.

Press the new strainer into the opening from above, pushing it down firmly so the putty or caulk spreads evenly. From underneath, thread the locknut back onto the strainer's threaded post and tighten it by hand first. Then use a basin wrench or adjustable wrench to snug it—firm enough that it doesn't wiggle, but not so tight that you crack the plastic fitting. Wipe away any excess putty or caulk with a damp cloth.

Reconnect the tailpiece and trap

The tailpiece is the pipe that screws directly to the strainer. Screw it back on by hand, then use a wrench to tighten the connection. Again, snug is better than cranked—you're aiming for no leaks, not maximum force.

Now reconnect the trap. The slip nut you removed earlier threads back onto the tailpiece. Hand-tighten it first, then use a wrench to snug it. If the trap is old and corroded, you may want to replace it too—a new plastic trap costs $10 to $20 and is easier to work with than metal.

Test for leaks before you call it done

Turn the shutoff valve back on (counterclockwise) and run water into the sink. Watch underneath for drips at the locknut, the slip nut, and where the tailpiece screws into the strainer. If you see water, tighten that connection a quarter turn with a wrench and check again. Small weeps often stop once the water pressure settles.

Let the water run for a minute, then fill the sink and let it drain. Watch the trap area again. If water is still dripping after 10 minutes of running water, turn off the shutoff valve, dry the area with a towel, and tighten the leaking connection another quarter turn. Repeat until the leak stops.

When to stop and call a plumber

If the old locknut won't budge even after you've sprayed it with penetrating oil and waited 15 minutes, or if you crack a plastic fitting while tightening, stop. Forcing it risks breaking the sink itself or stripping the threads. A plumber can remove a stuck locknut with specialized tools and won't charge much for a straightforward drain swap—usually $150 to $300 depending on your area.

Also call a plumber if water is leaking from inside the wall or if the trap itself is corroded through and leaking. Those are signs of a bigger problem that a new drain assembly alone won't fix.

Frequently Asked Questions

Do I need plumber's putty or can I use caulk?

Either works. Plumber's putty is easier to remove if you need to take the drain apart later—you just peel it away. Silicone caulk lasts longer and is more water-resistant, but you'll need a caulk remover or knife to get it out next time. For a kitchen sink you plan to keep for years, silicone is the better choice.

What if my sink has two drains?

A double sink has two separate strainer assemblies, but they share one trap underneath. Replace each strainer the same way, then reconnect both tailpieces to the shared trap using a tee fitting (a Y-shaped connector). The hardware store will have the right size when you show them your sink.

Can I replace just the strainer basket without taking apart the whole drain?

Yes, if only the basket is cracked or damaged. Unscrew the locknut from underneath, push the old basket out from above, and press the new one in with a fresh bead of putty or caulk. Screw the locknut back on and you're done—no need to touch the tailpiece or trap.

Why is my new drain leaking at the locknut even after I tightened it?

The rubber or plastic washer inside the locknut may be missing or damaged. Turn off the water, unscrew the locknut, and check if there's a washer under it. If not, buy a replacement washer at the hardware store, slip it onto the threaded post, and screw the locknut back on. If the washer is there but cracked, replace it.

How tight should the locknut be?

Tight enough that the strainer doesn't wiggle when you push on it from above, but not so tight that you need all your strength to turn the wrench. A quarter turn past hand-tight is usually right. If you over-tighten a plastic fitting, you'll hear a cracking sound—back off when ready and replace the fitting.