arrow_back
STUCKFIX
handymanDIY Friendly
leak_add

Kitchen Sink Basket Strainer Leaking Underneath

Water dripping from the basket strainer under your kitchen sink means a dried-out gasket or loose locknut. Tighten or replace the seal before it rots the cabinet floor.

Category:Kitchen
Difficulty:Easy
Time:15-20 min
Success:50%
Updated:May 22, 2026

quick_referenceQuick Answer

For Kitchen Sink Basket Strainer Leaking Underneath, start with "Dry everything and find the exact leak point": Clear out everything from under the sink, wipe all the pipes and the bottom of the sink dry with paper towels. Fill the sink with a few inches of water, then pull the plug and watch underneath with a flashlight. The leak will either be coming from between the strainer body and the sink (the top gasket has failed), or from around the locknut threads (the bottom gasket is shot), or from a loose slip nut on the tailpiece. Know which one before you start turning wrenches. Stop DIY if the sink hole is rusted or corroded around the drain opening — the putty and gasket need a clean flat surface to seal. This is listed as a easy recovery and usually takes about 15-20 min.

verifiedGuide Snapshot

Repair areaKitchen
Estimated time15-20 min
DifficultyEasy
Stop conditions3

Last updated May 22, 2026. Review the stop conditions before continuing.

account_treeRecovery State

DeviceKitchen Sink
Current stateBasket Strainer Leaking
Specific stateGasket Failure Under Sink
Failed stepStrainer Seal Inspection
Likely failure typeLeak Path
DIY boundaryDIY recovery first
paymentsCost decision

help1. Understand the Problem

The basket strainer is the metal assembly in the sink drain opening that catches food scraps. Under the sink, it's held tight against the sink bottom by a large locknut and a rubber gasket. Over time, the gasket dries out and cracks, or the locknut loosens from the vibration of running water and disposal use. The result is a slow drip that runs along the bottom of the sink and onto the cabinet floor. It's a small leak until the cabinet floorboard swells up and you're replacing the whole sink base.

build_circle2. Try This First

Best First Step

Dry everything and find the exact leak point

Clear out everything from under the sink, wipe all the pipes and the bottom of the sink dry with paper towels. Fill the sink with a few inches of water, then pull the plug and watch underneath with a flashlight. The leak will either be coming from between the strainer body and the sink (the top gasket has failed), or from around the locknut threads (the bottom gasket is shot), or from a loose slip nut on the tailpiece. Know which one before you start turning wrenches.

visibility3. Visual Guidance

See what's happening and how to try the first recovery step.

1
image
Tighten the locknut firstSometimes the fix really is just a loose nut. The large locknut under the sink holds the strainer against the sink bottom. Use a strainer wrench or a pair of large channel locks to tighten it clockwise. Go snug — don't gorilla it. If the leak stops, you're done. If not, the gasket is gone.
2
image
Replace the strainer assembly if tightening failsIf tightening doesn't stop the leak, the rubber gasket has dried out or the plumber's putty seal above has broken. You'll need a new basket strainer assembly — they're $8-15 at any hardware store. Loosen the locknut, push the old strainer up from underneath, and clean the sink hole thoroughly with a scraper. Roll a rope of plumber's putty between your palms and press it around the underside of the new strainer flange. Drop it in, tighten the new locknut from below, and wipe off the excess putty that squeezes out.
3
image
Double-check with a leak testOnce installed, reattach the tailpiece to the strainer, tighten all slip nuts, then run a full sink of water and pull the plug. Watch underneath for a full minute after the water drains — leaks can be slow and intermittent. Check that water isn't leaking from the slip nut where the strainer thread meets the tailpiece too.

autorenew4. If That Doesn't Work

Try the next recovery options.

build
Replace just the gasket if the strainer body is fineIf the strainer itself is in good shape (no rust, no cracks), you can sometimes get away with replacing just the rubber gasket and the plumber's putty. Clean the old strainer thoroughly, apply new putty on top and a new gasket underneath.
chevron_right
upgrade
Upgrade to a stainless steel strainerIf you have a cheap plastic or thin chrome-plated strainer that keeps leaking, upgrade to a heavy-gauge stainless steel basket strainer. They're $15-25 and the threaded body is machined more precisely than the cheap ones.
chevron_right

Frequently Asked Questions

Do I need plumber's putty or silicone for a basket strainer?expand_more
Plumber's putty. It stays flexible and allows the strainer to be removed later. Silicone will work but makes it nearly impossible to remove the strainer without destroying it. The only exception is natural stone sinks — use silicone for those as the oils in plumber's putty can stain the stone.
Can I reuse the old basket strainer with new putty?expand_more
Yes, if the strainer body isn't rusted, cracked, or bent. Clean the old putty off completely with a scraper, apply a fresh rope of new putty, and use a new rubber gasket underneath. The gasket is what usually fails, not the metal strainer body.
How tight should the basket strainer locknut be?expand_more
Hand-tight plus about a quarter turn with a wrench. Overtightening can distort the rubber gasket, crack the plastic locknut, or pull the strainer so tight that the plumber's putty all squeezes out and the seal fails.

warning5. Stop DIY If

Don't continue if any of these apply.

reportThe sink hole is rusted or corroded around the drain opening — the putty and gasket need a clean flat surface to seal.
reportThe strainer threads are cross-threaded and the locknut won't engage properly — you may need a new strainer.
reportThe leak continues after two attempts with new parts and fresh putty — there may be a hairline crack in the sink itself.
Still stuck?Get personalized help with AI Recovery.

Related Recovery Problems

View all arrow_forward
Under-Sink Valve Seized? Don't Force It. Try ThisGarbage Disposal Hums But Won't Spin? Try These Recovery ActionsKitchen Sink Drains Like Molasses? Grease Blockage Recovery GuideKitchen Sink Sprayer Won't Turn Off After Using It

Same Device Recovery States

Device index arrow_forward
air_freshener
Sink drain smellsA kitchen sink drain that stinks usually has rotting food sludge in the P-trap or a dried-out garbage disposal. Clean it in 10 minutes with stuff under the sink.

Similar Failure Pattern

Water hammer noiseWasher door leakLeaking PVC jointDisposal bottom leak

This page provides general DIY guidance.
If you're unsure, it's always best to consult a professional.