Step-by-step fix
Step 1: Make sure the basket strainer is the problem
- Look under the sink and dry the drain area, tailpiece, and trap with a rag.
- Run a small amount of water into the sink, then watch where fresh water first appears.
- Check for leaking right at the sink drain opening or around the strainer body, not farther down at the trap or supply lines.
- Inspect the basket strainer from above for rust, pitting, a loose flange, missing parts, or old putty squeezing out unevenly.
If it works: You confirmed the leak or damage is centered at the basket strainer assembly.
If it doesn’t: If the leak starts at a slip-joint nut, trap, dishwasher branch, or faucet connection, fix that part instead of replacing the basket strainer.
Stop if:- The sink metal around the drain opening is cracked, badly rusted through, or bent enough that a new strainer will not seat flat.
- The drain piping is frozen in place and starts twisting inside the wall when you try to loosen it.
Step 2: Set up the sink and disconnect the drain below
- Clear out the cabinet so you can work directly under the sink.
- Place a bucket or shallow pan under the trap area.
- If the sink has a stopper or basket, remove it from above.
- Loosen the slip nut or connection that ties the tailpiece to the drain below the strainer, then move the drain parts down or aside enough to free the strainer assembly.
- Support the piping with one hand as you loosen connections so you do not strain other joints.
If it works: The drain below the basket strainer is disconnected and out of the way.
If it doesn’t: If a slip nut is stuck, try steady pressure with pliers while holding the adjoining pipe so the rest of the drain does not twist.
Stop if:- A metal drain arm in the wall or disposal connection starts moving with the nut and may break loose.
- You find severe corrosion or cracked drain parts that need broader drain repair before reassembly.
Step 3: Remove the old basket strainer
- From below, loosen the large locknut or mounting nut that holds the basket strainer to the sink.
- If the strainer body spins, hold it from above with pliers or a strainer tool while turning the nut below.
- Remove the friction ring, gasket, and mounting pieces in order and set them aside so you can compare them to the new parts.
- Push the old basket strainer up and out through the sink opening.
- Scrape old plumber's putty and residue off the sink surface and the drain opening until both are clean and smooth.
If it works: The old basket strainer is out and the sink opening is clean.
If it doesn’t: If the old putty is stubborn, soften and scrape it a little at a time until the metal or sink surface is clean enough for a fresh seal.
Stop if:- The sink opening is misshapen, deeply pitted, or damaged enough that the new flange cannot sit flat.
Step 4: Install the new basket strainer and seal it
- Compare the new basket strainer parts to the old assembly so you understand the order before tightening anything.
- Roll plumber's putty into a rope and press it under the new strainer flange unless the new part specifically uses a different included seal.
- Set the new basket strainer into the sink opening from above and press it down evenly.
- From below, install the gasket, friction ring, and locknut in the order provided with the new strainer.
- Hold the strainer centered while tightening the locknut until the flange is snug and putty squeezes out evenly around the top.
- Wipe away the excess putty from the sink surface.
If it works: The new basket strainer is seated flat, centered, and firmly sealed to the sink.
If it doesn’t: If the flange looks crooked or the putty squeezed out heavily on one side only, loosen it and reset the strainer before reconnecting the drain.
Stop if:- The replacement parts do not match the sink opening or the tailpiece connection size well enough to assemble without forcing them.
Step 5: Reconnect the drain and tighten everything evenly
- Reconnect the tailpiece or drain connection below the new basket strainer.
- Make sure washers and slip-joint connections are seated straight before tightening.
- Tighten the connections firmly but do not overtighten plastic nuts or thin metal parts.
- Wipe all joints dry so any new leak will be easy to spot.
- Remove tools and the bucket from directly under the fittings so you can watch the joints clearly during testing.
If it works: The drain assembly is back together and ready for a leak test.
If it doesn’t: If the tailpiece does not line up cleanly, loosen nearby slip joints, realign the drain, and then retighten so the parts meet without side pressure.
Stop if:- The drain piping cannot be aligned without forcing it sideways or leaving cross-threaded connections.
Step 6: Test the repair in real use
- Run water around the basket strainer while watching underneath for drips at the flange, locknut area, and tailpiece connection.
- Fill the sink partway, then release the water to test the drain under a heavier flow.
- Dry the area again and check a second time after a few minutes.
- Press lightly around the strainer from above to make sure it does not shift or spin.
If it works: No water appears around the basket strainer or drain connections during filling, draining, or normal sink use.
If it doesn’t: If water shows at the top flange, the strainer usually needs to be removed and resealed. If water shows lower down, retighten or reseat the drain connection that is leaking.
Stop if:- The sink still leaks from the drain opening after resealing, which points to sink damage, a mismatched part, or a larger drain assembly problem.
Replacement Parts
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FAQ
Do I need plumber's putty for every kitchen sink basket strainer?
Many basket strainers use plumber's putty under the top flange, but some come with a different sealing gasket or sealant instruction. Follow the sealing method included with the new part.
Why does the sink still leak after I tightened the new strainer?
The most common causes are a dirty sink opening, uneven putty, a crooked flange, or a leak that is actually lower at the tailpiece or slip-joint connection. Dry everything and pinpoint the exact source before retightening.
Can I reuse the old gasket or mounting hardware?
It is better to use the new hardware that comes with the replacement basket strainer. Old gaskets and rings may be compressed, brittle, or the wrong fit for the new assembly.
What size basket strainer do I need?
Match the replacement to your sink opening and drain connection. Compare the old assembly and check the product dimensions before buying so the flange, body, and lower connection all fit your sink.
Should I replace other drain parts at the same time?
If the tailpiece, slip nuts, or trap washers are cracked, badly corroded, or leaking, it makes sense to replace those worn parts while the drain is already apart.