How Do You Replace a Leaking Kitchen Sink Strainer Basket?

To replace a leaking kitchen sink strainer basket, disconnect the PVC drain pipe below the sink, unscrew the large metal locknut holding the old strainer in place, and push the old assembly up through the sink basin. Scrape away the old, dried putty, wipe the drain hole completely dry, and roll a half-inch thick rope of fresh plumber's putty to press around the sink opening. Drop the new strainer into the hole, slide the rubber washer and paper friction gasket onto the threads underneath, and tighten the new locknut until the putty squeezes out evenly inside the sink. Finally, reconnect your PVC drain pipe and test the system with standing water. Handling this hardware replacement yourself takes about an hour and costs a fraction of a professional plumber's minimum service call. If you have a bucket, a pair of large slip-joint pliers, and a fresh tub of putty, you already have the skills to execute a watertight, permanent fix.

• A standard 3-1/2 inch (8.8 cm) stainless steel strainer costs $15 to $35 in 2026, saving you a $150 to $250 plumber service fee.
• Always install the paper friction ring between the rubber gasket and the metal locknut to prevent the rubber from tearing during tightening.
• Plumber's putty is the standard top seal for stainless steel and cast iron sinks, but porous composite sinks require a specialized foam or rubber gasket instead.
• Test your finished work by filling the sink basin with several inches of water before pulling the stopper to simulate heavy drain pressure.

Why is the kitchen sink strainer leaking in the first place?

The strainer basket bridges the gap between your metal or composite sink basin and your PVC plumbing system. Because it sits at the bottom of a heavy-use basin, it is constantly subjected to temperature fluctuations from boiling pasta water and ice, chemical exposure from dish soaps, and severe micro-vibrations from nearby garbage disposals.

Over several years, these factors cause the plumber's putty on the top side of the sink to dry out, crack, and wash away. Simultaneously, the large rubber gasket on the underside of the sink compresses and loses its elasticity. Once the large metal locknut holding the whole assembly together backs off even a fraction of a millimeter due to vibration, water will bypass the top seal and drip steadily into your cabinet below. Since patching the old assembly from the bottom never holds back standing water, a full replacement is the only reliable fix.

• Dried, brittle plumber's putty that has lost its waterproofing capabilities.
• A compressed, aged rubber gasket that no longer applies upward pressure.
• Micro-vibrations that have slowly loosened the main assembly locknut.

What tools and materials do you need for this replacement?

For a standard United States residential kitchen, you will need a 3-1/2 inch (8.8 cm) basket strainer assembly. In 2026, a heavy-duty 304 stainless steel strainer with a brass locknut costs between $15 and $35. You will also need a small tub of traditional plumber's putty, which costs about $4. To remove the old plumbing and install the new unit, grab a bucket, a rag, a plastic putty knife, and a large pair of slip-joint pliers (often called Channellocks).

This is where a professional makes a distinctly different judgement call than a beginner. A beginner often reaches for silicone caulk to seal the top of the new strainer, assuming a permanent glue will prevent leaks better than a clay-like putty. A pro uses traditional plumber's putty on stainless steel and cast iron sinks. Putty stays pliable, allows the strainer to center itself perfectly as you tighten the nut, makes future replacements vastly easier, and requires zero curing time. You can run water over putty immediately, whereas silicone requires 24 hours to cure before you can use your kitchen sink again. Note: If you have a matte granite composite sink, oil-based putty will leave a permanent dark stain. For composite sinks, you must use the specialized foam or rubber top gasket that comes in the box.

• 3-1/2 inch (8.8 cm) stainless steel basket strainer assembly.
• Small tub of fresh plumber's putty (unless installing on composite stone).
• Large slip-joint pliers or a dedicated drain spud wrench.
• Plastic putty knife and a bucket for catching residual water.

How do you remove the old, stuck strainer basket?

Clear out everything under your kitchen sink and place a bucket directly under the drain tailpiece. Start by loosening the plastic or metal slip nut that connects the 1-1/2 inch (3.8 cm) vertical drain pipe to the bottom of the strainer. Turn it counterclockwise by hand or use your slip-joint pliers if it is stuck. Pull the PVC pipe downward and out of the way.

Next, tackle the large metal locknut securing the strainer to the underside of the sink. These are often corroded or frozen in place. Grip the ridges of the locknut with your large slip-joint pliers and turn counterclockwise. If the entire strainer basket begins to spin in the sink hole as you turn the nut, have a helper insert the handles of a pair of pliers down into the crosshairs of the strainer from above to hold it still. Once the locknut is completely unthreaded, push the strainer assembly firmly upward to break the old putty seal and lift it out of the sink basin.

• Place a catch bucket to collect residual water in the P-trap.
• Disconnect the 1-1/2 inch (3.8 cm) tailpiece slip nut.
• Unthread the large retaining locknut from the strainer body.
• Push the old assembly up and out of the basin.

How do you prep the sink drain hole for the new strainer?

The single most common failure mode in this project is installing the new strainer directly over bits of old, calcified putty or soap scum. If the stainless steel sink lip is not perfectly smooth, the new putty cannot form a watertight seal, and the new strainer will leak on day one.

Use a plastic putty knife to scrape away the ring of old putty from the top of the sink. Avoid using a metal screwdriver or steel scraper, which will scratch a stainless sink and create tiny channels for water to escape. Once the heavy debris is gone, use an abrasive sponge and rubbing alcohol to wipe the drain hole down to bare, shining metal. Dry the area completely with a paper towel. Plumber's putty will not adhere properly to a wet surface.

• Scrape away old putty using a plastic, non-marring tool.
• Scrub away invisible soap scum with rubbing alcohol.
• Dry the sink hole completely before applying new sealant.

How do you install the new strainer basket so it never leaks?

Take a golf-ball-sized scoop of fresh plumber's putty and roll it between your palms to create a snake about 1/2-inch (1.3 cm) thick. Wrap this putty rope completely around the underside of the new strainer basket's top flange, overlapping the ends slightly. Press the strainer firmly down into the drain hole. Do not worry about the putty squeezing out into the sink basin; that means you used enough.

Move under the sink to build the bottom assembly. Your new strainer kit includes a thick rubber washer and a thin cardboard or paper friction ring. Slide the rubber washer onto the strainer threads first, pushing it flush against the underside of the sink. Slide the paper friction ring on immediately after it. Thread the large metal locknut onto the strainer.

Failing to install the paper friction ring is a classic beginner mistake. As you tighten the metal nut against bare rubber, the friction will grab the rubber washer, twisting and warping it out of shape. The paper ring allows the metal nut to spin smoothly against the rubber, compressing it evenly upward without tearing it. Use your large pliers to tighten the locknut firmly. Stop when the strainer feels rigidly seated. Go back up top and peel away the excess putty that has squeezed out into the sink.

• Roll a 1/2-inch (1.3 cm) continuous rope of plumber's putty.
• Press the strainer into the hole to squeeze out the excess.
• Install the rubber washer first, followed by the paper friction ring.
• Tighten the locknut firmly without warping the rubber gasket.

How do you reconnect the plumbing and test for leaks?

Locate the flanged top of your 1-1/2 inch (3.8 cm) PVC tailpiece. If the plastic top-hat washer inside the slip nut looks deformed or brittle, replace it now for about fifty cents. Slide the tailpiece up to the threaded bottom of the new strainer basket and hand-tighten the slip nut. Once it is hand-tight, give it one extra quarter-turn with your slip-joint pliers.

To test your work properly, do not just run the faucet. Drop the stopper into the new strainer and fill the sink basin with 3 inches (7.6 cm) of water. Let it sit for five minutes while you watch the underside with a flashlight to ensure the putty seal holds. Then, pull the stopper and let the heavy volume of water rush down the drain. This surge creates pressure inside the PVC tailpiece, which will immediately reveal if your slip nut connection is secure. If a drip appears, tighten the offending nut another eighth of a turn.

• Replace the cheap plastic slip joint washer if it looks warped.
• Tighten the slip nut by hand, plus one quarter-turn with pliers.
• Test the upper putty seal with 3 inches (7.6 cm) of standing water.
• Test the lower slip nut seal by draining a high volume of water at once.

Frequently asked questions