A leaking kitchen sink will lead to water damage in the cabinet as well as the room that sits below the kitchen. Once you notice that water leaks from the bottom of the sink, you need to stop using it until you can locate and fix the leak, or you risk further damaging your house.
Locate the Leak
Leaks from pipes or the bottom of your kitchen sink can provide a challenge since the water can run along pipes for a distance before dripping down to the cabinet below the sink. Before you start repairing things that do not need to be fixed, use a simple test to locate the source of the leak. Dry the bottom of the sink and the drain piece as well as the drain pipes. Fill the sink with water, and hold a tissue over the area you suspect is leaking. Try the test until the tissue becomes wet, indicating it is over the leak.
Tighten Pipe Connections
If you find that the connections between pipes, or even between the sink's drain basket and the pipe, is the cause of the leak, you can tighten the connection to stop the leak. With plastic pipes you will want to hand-tighten them as much as possible. If the leak continues, tighten the pipe connections in small increments using a pipe wrench. You must use the pipe wrench to tighten the connections for metal pipes, but stop turning the wrench once you feel resistance from the pipes.
Remove the Strainer
If the strainer or drain piece is the source of the leak, you must first use an adjustable wrench to remove the coupling nut from the strainer. You must use a spud wrench to remove the locknut from the bottom of the strainer next. You can insert the handles of a pair of pliers into the grates of the drain piece if it spins, and while you are trying to remove the coupling nut and locknut, thread a screwdriver through the handles of the pliers to keep the drain stationary. Once you have removed the strainer, use a plastic putty knife to scrape off any remaining old plumber's putty.
Install a New Strainer
You must first make a rope out of plumber's putty, and wrap it around the drain opening in the bottom of the sink. With the putty in place, press the drain piece into place. Thread the locknut onto the drain, and tighten it with pliers, and then tighten the coupling nut onto the bottom of the drain piece. You can use your hands or the pipe wrench to attach the drainpipe to the bottom of the new drain piece. You will also need a rag to wipe away any plumber's putty that squeezes out from between the sink and the drain piece.