How to Install a Kitchen Sink Basket Strainer

Start by clearing everything out from under the sink to give yourself ample workspace. Place a bucket directly beneath the P-trap to catch any water that will spill out. Use channel-type pliers to loosen the slip nuts connecting the tailpiece to the basket strainer and the P-trap. Once loose, disconnect the tailpiece and set it aside. Next, use the pliers or a strainer locknut wrench to loosen and remove the large locknut holding the old strainer to the underside of the sink. You may need a helper to hold the strainer from above with a screwdriver or pliers to prevent it from spinning. Once the locknut is off, push the old strainer up and out of the sink.

After removing the old strainer, thoroughly clean the top and bottom surfaces of the sink's drain opening. Use a putty knife to carefully scrape away any old, hardened plumber's putty or sealant residue. Follow up with a rag and a mild cleaning solvent or mineral spirits to remove any remaining film, ensuring the surface is completely clean and dry. A clean surface is crucial for creating a perfect seal with the new strainer.

Take a small amount of plumber's putty from its container and knead it in your hands for about a minute to warm it up and make it pliable. Roll the putty between your palms to form a uniform, rope-like snake about 1/2-inch thick. The rope should be long enough to encircle the drain opening completely. Carefully press this rope of putty onto the underside of the new strainer's flange, ensuring it forms a continuous, unbroken ring.

With the plumber's putty applied, firmly press the new basket strainer down into the sink's drain opening from above. Push it down evenly so that some of the putty squeezes out around the entire perimeter of the flange. This squeeze-out indicates a good seal. The strainer should sit flush and be centered in the opening.

From underneath the sink, place the components onto the threaded body of the strainer in the correct order. First, slide on the rubber gasket, ensuring its flat side is against the sink bottom. Next, add the friction washer (this is often made of paper or fiber). Finally, thread on the metal locknut by hand until it is finger-tight. Ensure the gaskets and washer are centered and flat against the underside of the sink.

Ask a helper to hold the strainer steady from above by inserting the handles of pliers or a screwdriver into the crossbars of the strainer body. From below, use channel-type pliers or a specialized strainer locknut wrench to tighten the locknut. Tighten it firmly to compress the putty and the rubber gasket, creating a watertight seal. Be careful not to overtighten, which could crack the sink or the strainer. A good rule of thumb is to tighten until snug, then an additional quarter to half turn.

Once the locknut is tight, go back to the top side of the sink. Use your finger or a putty knife to carefully remove the excess plumber's putty that has squeezed out around the flange. Wipe the area clean with a soft rag for a neat finish.

Reattach the drain tailpiece to the bottom of the new basket strainer. If the old tailpiece is in poor condition, now is a good time to replace it. Ensure the slip nut washer is in place and oriented correctly (tapered side facing the flare of the tailpiece). Hand-tighten the slip nuts connecting the tailpiece to the strainer and the P-trap. Give them a final quarter-turn with channel-type pliers, but be careful not to overtighten plastic threads.

With everything reassembled, it's time to test your work. Place the stopper in the sink drain and fill the sink basin with several inches of water. Let it sit for a few minutes, checking underneath with a flashlight and a dry paper towel for any drips around the new locknut or the drain connections. Then, pull the stopper and let the water drain out quickly, again checking for leaks as the water flows through the pipes. If you see any drips, you may need to slightly tighten the corresponding nut or, in a worst-case scenario, disassemble and reseat the strainer.