How to Install a Kitchen Sink Basket Strainer
Replace a leaky kitchen sink basket strainer using plumber's putty and a secure locknut installation to create a watertight seal.
- Read the tools, materials, safety notes, and steps below for free.
- Tap Start Camera Coach when you want hands-free voice help.
- Allow camera and microphone. Point your phone at the work; the coach watches your progress and tells you the next step.
🧰 Required Tools & Equipment
- ✓ Plumber's basket strainer wrench
- ✓ Tongue-and-groove pliers (Channel locks)
- ✓ Putty knife
- ✓ Flathead screwdriver
- ✓ Bucket
- ✓ Rag or shop towels
📦 Materials & Supplies
- ✓ New sink basket strainer assembly
- ✓ Plumber's putty (or 100% silicone for granite/composite)
- ✓ Rubber gasket
- ✓ Friction washer (cardboard or paper ring)
⚠️ Safety Checkpoints & Warnings
- • Turn off under-sink water supply valves and place a catch bucket before disassembly.
- • Wear eye protection when working overhead inside the dark sink cabinet to guard against falling rust and debris.
- • Check sink basin material compatibility before applying plumber's putty; granite/quartz can stain from oils in putty.
📋 Step-by-Step Guide (7 Steps)
Remove Existing Strainer and Clean Basin Opening
Place a bucket under the drain pipes. Loosen the slip nut connecting the tailpiece to the P-trap with tongue-and-groove pliers, then unscrew the large locknut beneath the sink strainer. Remove the old strainer body, scrape off dried putty using a plastic or brass putty knife, and wipe the sink opening completely clean and dry.
- • Empty drain hole in the sink with bare, shiny stainless steel or clean porcelain rim
- • P-trap disconnected and resting cleanly over a drain bucket
- • Using a metal screwdriver to scrape old putty, scratching the sink surface
- • Leaving moisture or old sealant residue around the mounting hole
Apply Plumber's Putty Ring
Roll a golf-ball-sized clump of plumber's putty between your palms until it forms an even rope about 1/2-inch thick. Press this rope firmly around the underside lip of the new basket strainer flange, forming a continuous ring with no gaps.
- • A uniform, unbroken ring of plumber's putty encircling the underside lip of the new strainer body
- • Making the putty rope too thin, causing voids under the flange
- • Using dried or crumbling putty instead of fresh, pliable compound
Seat Strainer Body into Basin Hole
Lower the strainer body straight down into the sink drain opening. Press down firmly and evenly with both hands so putty squeezes out around the perimeter. Do not twist the strainer once pressed down, as twisting can create air channels.
- • Strainer flange sitting flat and parallel against the sink bottom
- • Continuous bead of excess putty oozing out 360 degrees around the rim
- • Rotating the basket strainer after seating it
- • Pressing down unevenly, making one side sit higher than the other
Install Under-Sink Gaskets and Locknut
Underneath the sink, slide the thick rubber gasket up against the sink bottom first, followed by the friction washer (cardboard or plastic ring). Thread the large metal locknut onto the strainer body threads and hand-tighten it clockwise until snug against the friction ring.
- • Layering order is correct: sink underside, rubber gasket, friction washer, metal locknut
- • Locknut threaded flat and straight onto the strainer body
- • Placing the friction washer between the rubber gasket and the sink basin
- • Cross-threading the large locknut on the thin strainer threads
Tighten Locknut and Secure Assembly
Use a basket strainer wrench or large channel lock pliers to tighten the locknut firmly. Have a helper hold the top strainer body in place with pliers handles, or use a strainer tool to prevent the entire unit from spinning. Tighten until the rubber gasket compresses firmly without bulging out of shape.
- • Rubber gasket compressed uniformly around the entire underside diameter
- • Locknut fully tightened and seated flat against the friction ring
- • Over-tightening until the rubber gasket completely extrudes or tears
- • Allowing the top strainer body to spin, breaking the putty seal
Clean Excess Putty and Reconnect Drain Piping
Use a plastic putty knife or a clean rag to remove the bead of excess putty that squeezed out around the top rim, returning excess to the container. Reconnect the drain tailpiece and P-trap under the sink, ensuring the slip joint washers are facing the correct direction, and hand-tighten slip nuts followed by a quarter-turn with pliers.
- • P-trap and tailpiece fully joined with straight, aligned slip joints
- • Sink basin floor spotless with no residual putty around the strainer rim
- • Installing conical slip joint washers backward (bevel must face toward the receiving joint)
- • Over-tightening plastic slip nuts, causing threads to strip
Test for Leaks Under Full Water Load
Insert the sink stopper and fill the sink basin halfway with water. Check underneath with a dry paper towel for immediate drips; then pull the stopper to release a high-volume rush of water through the drain while inspecting every connection point below.
- • Water draining freely with no droplets forming on the strainer locknut or pipe joints
- • Dry paper towel wiped along the underside joints remains completely dry
- • Only running a trickle of water rather than testing with head pressure from a full sink
- • Touching wet hands to the pipes instead of using a dry paper towel to spot small seeps
Credit: inspired by an original tutorial by jeffostroff — watch the original on YouTube.
Don’t have everything?
- No Plumber's basket strainer wrench? Large 12-inch tongue-and-groove pliers or flathead screwdriver tapped against locknut lugs
- No Plumber's putty? 100% silicone sealant (required for porous stone/granite sinks)