Replace a sink strainer by first removing the old sink strainer, preparing the new drain and sink strainer, and applying plumber's putty to the base of the strainer. After that, install the new sink strainer and reinstall the drain pipes.
A leak under the kitchen sink often means it's time to replace the sink strainer. If there is a leak, first locate the source of it. If it is coming from where the sink and drain come together, then the sink strainer is the cause. To replace the sink strainer, you need a new sink strainer, pliers and plumber's putty.
Remove the pipes connected to the old sink strainer. Once the fittings are off, remove the old strainer nut with pliers. After removing the nut, pull the old strainer out from the top of the sink. To prepare the new drain and sink strainer, spread out the various parts of the basket strainer within reach, and loosen the screws on the retainer.
Wrap a generous amount of plumber's putty around the base of the strainer on the underside of the lip. Set the strainer into the sink drain, centering it and aligning it as needed. Push it down enough so that the plumber's putty slightly adheres to the sink. Working from the underside of the sink, place the flexible washer and then the metal washer into place over the body of the sink strainer. While holding them in place, thread the retainer on all the way, and then tighten the screws.
Finally, reinstall the drain pipes in the opposite order of removal, and turn the water on.