What You Need to Do Before You Start

A kitchen sink strainer is the basket that sits in the drain opening and catches food scraps. When it cracks, rusts, or stops holding debris, you replace it by unbolting the old one from underneath the sink and screwing in a new one. The whole job takes about 30 minutes and requires only basic tools you likely have at home—no plumber needed.

Before you begin, turn off the water supply under the sink by turning the shutoff valves clockwise (one for hot, one for cold). If your sink has a garbage disposal, turn off the power at the wall switch or circuit breaker. Place a bucket under the drain to catch any standing water that spills when you disconnect the pipes.

Buy a replacement strainer basket that matches your sink type. Most kitchen sinks use a standard 3.5-inch strainer, but measure the opening of your drain to be sure. Bring a photo of your current strainer to the hardware store if you are unsure which one to buy.

Key Takeaways

  • Turn off water at the shutoff valves under the sink and place a bucket underneath before you start disconnecting anything.
  • The strainer bolts to the sink from underneath using a locknut and friction ring—you will need a basin wrench or adjustable wrench to remove these.
  • explore plumber's putty around the new strainer's underside before you insert it into the drain opening to create a watertight seal.
  • Tighten the locknut hand-tight first, then use a wrench to snug it another quarter turn—over-tightening can crack the sink.

Disconnect the P-Trap and Tailpiece

Slide under the sink with a flashlight and locate the curved pipe (the P-trap) that connects to the straight pipe (the tailpiece) coming down from the strainer. Use an adjustable wrench or pipe wrench to loosen the large nut where the P-trap connects to the tailpiece. Turn it counterclockwise by hand once it is loose enough to grip.

Unscrew the nut completely and pull the P-trap down and away. Water will drip—that is why the bucket is there. If your sink has a garbage disposal, the tailpiece will be connected to the disposal instead of directly to the strainer. Disconnect it the same way, using a wrench on the large nut.

Once the tailpiece is free, you can access the locknut and friction ring that hold the strainer to the sink from below. Set the disconnected pipes aside in the bucket so they do not drip on your floor.

Remove the Old Strainer Basket

Look up at the underside of the sink. You will see a large nut (the locknut) threaded onto the strainer body, with a rubber or metal ring (the friction ring) sitting between the nut and the sink. Use a basin wrench to grip and turn the locknut counterclockwise. A basin wrench is a specialized tool with a long handle that fits into tight spaces—you can rent one from a hardware store for a few dollars, or use an adjustable wrench if you have room to work.

Turn the locknut until it comes off completely. The friction ring may fall—catch it so you do not lose it. Once the nut is off, reach up into the sink from above and push the old strainer basket up and out. It should come free easily. Scrape away any old plumber's putty or caulk from the underside of the sink opening using a putty knife or old credit card.

Install the New Strainer Basket

Roll a rope of plumber's putty about the thickness of a pencil and press it around the underside of the new strainer's rim. This putty creates a watertight seal between the strainer and the sink. Do not skip this step—without it, water will leak into the cabinet below.

Insert the new strainer basket into the drain opening from above, pushing it down until it sits flush with the sink surface. Reach underneath and slide the friction ring onto the strainer body, then thread the locknut on by hand. Tighten it clockwise until it is snug, then use your basin wrench to turn it another quarter turn. Stop there—do not over-tighten, which can crack the sink or strip the threads.

Wipe away any excess putty that squeezes out around the rim of the strainer with a damp cloth. The strainer should not move or wiggle when you push on it from above.

Reconnect the Tailpiece and P-Trap

Slide the tailpiece back onto the strainer body from underneath. Hand-tighten the large nut, then use your wrench to snug it another quarter turn. Do the same with the P-trap connection—hand-tight first, then a quarter turn with the wrench. Both connections should be firm but not cranked down hard.

Turn the water back on at the shutoff valves by turning them counterclockwise. Let the water run for 30 seconds and watch underneath the sink for drips at the locknut, the tailpiece connection, and the P-trap connection. If you see water dripping, turn off the water and tighten that connection another eighth turn with your wrench.

Test for Leaks and Clean Up

Fill the sink with water and let it drain completely while you watch underneath. The strainer basket should hold water briefly before it drains through the tailpiece. You should see no drips at any connection point. If water leaks from under the strainer rim itself, the putty seal may not be complete—you will need to remove the strainer, add more putty, and reinstall it.

Once you confirm there are no leaks, dry the area under the sink with a towel and return any items you removed. If your sink has a garbage disposal, turn the power back on at the wall switch or circuit breaker.

Common Mistakes to Avoid

The most common error is forgetting the plumber's putty, which causes water to leak into the cabinet. Another is over-tightening the locknut, which can crack porcelain or ceramic sinks. Hand-tight plus a quarter turn is the right amount of force.

Do not reconnect the P-trap before testing the strainer seal. If you do and it leaks, you will have to disconnect everything again. Also, do not use old plumber's putty that has dried out or become hard—buy a fresh container. Old putty will not seal properly and will crumble away over time.

Frequently Asked Questions

Do I need a basin wrench, or can I use a regular wrench?

A basin wrench is easier because it reaches into tight spaces under the sink, but a regular adjustable wrench works if you have room to maneuver. You may need to remove items from under the sink to make space. A basin wrench costs a few dollars to buy or rent.

What if the locknut is stuck and will not turn?

Spray the nut with penetrating oil (like WD-40) and wait 15 minutes. Try again with your wrench. If it still will not budge, tap the wrench handle gently with a hammer to break the corrosion loose, then try turning it. Do not force it hard enough to bend the wrench or damage the sink.

Can I replace just the strainer basket without removing the whole assembly?

No. The basket is permanently attached to the body that bolts to the sink. You must remove the entire assembly and replace it with a new one. The good news is that the whole strainer unit (basket, body, locknut, and friction ring) costs between $15 and $40 at most hardware stores.

How do I know if my strainer needs replacing?

Replace it if you see visible cracks or rust, if it no longer holds debris and lets food fall through, or if water leaks from around the rim even after you tighten the locknut. A strainer that is straightforward dirty can be cleaned with a brush and does not need replacement.

What is the difference between a standard strainer and a deep-basket strainer?

A deep-basket strainer holds more food scraps before it needs emptying, which is useful if you do a lot of food prep. A standard strainer is shallower. Both install the same way. Choose based on how much debris your sink typically collects.