How to Install a Kitchen Sink Basket Strainer

Begin by clearing everything from the cabinet under the sink to give yourself ample working space. Place a bucket directly underneath the P-trap assembly to catch any residual water that will spill out when you disconnect the pipes. Using a pair of channel-lock pliers, loosen the slip nuts connecting the P-trap to the strainer's tailpiece and the wall drain pipe. Once loose, you can usually finish unscrewing them by hand. Carefully lower the P-trap and empty any water into the bucket.

With the P-trap removed, you can now remove the old strainer. From underneath the sink, use your channel-lock pliers or a dedicated sink strainer wrench to loosen the large locknut holding the strainer assembly in place. You may need someone to hold the strainer from the top side of the sink to prevent it from spinning, or you can wedge the handles of a pair of pliers into the crossbars of the strainer. Once the locknut is removed, push the old strainer body up and out of the sink drain hole.

After removing the old strainer, thoroughly clean the area around the sink drain opening on both the top and bottom surfaces. Use a plastic putty knife to scrape away all the old plumber's putty or sealant residue. Be careful not to scratch the sink surface. Once the bulk of the old putty is gone, use a non-abrasive scouring pad and a mild cleaner or mineral spirits to remove any remaining film, then wipe the area dry with a clean cloth. A perfectly clean, dry surface is essential for a good seal.

Take a small canister of plumber's putty and warm a walnut-sized ball of it in your hands to make it more pliable. Roll the putty between your palms to form a uniform rope about 1/2-inch thick. The rope should be long enough to encircle the underside of the new strainer's flange (the top lip). Carefully press this rope of putty firmly onto the underside of the flange, ensuring it makes a complete, unbroken circle.

From the top of the sink, firmly press the new strainer body, with the plumber's putty applied, straight down into the clean drain opening. Apply even pressure to seat it properly. You should see a small amount of plumber's putty squeeze out around the edges of the strainer flange. This is a good sign, indicating a solid seal. Leave this excess putty for now; you will clean it up later.

Move back underneath the sink. Slip the components onto the threaded bottom of the strainer body in the correct order: first the fiber or cardboard friction washer, then the rubber gasket (tapered side up towards the sink), and finally the metal locknut. Hand-tighten the locknut as much as you can. The friction washer allows the locknut to turn without twisting the rubber gasket out of place.

While holding the strainer from above to prevent it from spinning (using pliers in the basket or a helper), use your channel-lock pliers or strainer wrench to tighten the locknut from below. Tighten it firmly to compress the rubber gasket and squeeze out the excess plumber's putty above the sink. A good rule of thumb is to give it a quarter-turn past hand-tight. Do not overtighten. Once tight, go above the sink and use your finger or a cloth to wipe away the excess putty that has squeezed out. Use the plastic putty knife for any stubborn bits.

With the new strainer securely installed, reattach the P-trap. Connect the tailpiece to the bottom of the new strainer and the other end of the trap to the drain pipe in the wall. Hand-tighten the slip nuts first to ensure they are not cross-threaded, then give them a final quarter-turn with the channel-lock pliers. Place the stopper in the sink drain, fill the sink basin completely with water, and check carefully under the sink for any drips from the new locknut or the reconnected trap fittings. Then, release the water and check again for leaks while the water is draining at full flow.