How to Repair a Leaky Sink Trap

What You'll Need
Slip joint pliers
Sink Trap (p-trap)
Sip Nuts

A leaky sink trap under your kitchen sink can cause mold and mildew. If the moisture under the sink is left undetected for too long it can cause rotting and other damage to the cabinet. Once you have discovered that you have a problem you can check your plumbing and determine the problem. Many repairs including replacing the sink trap are easy to do.

Step 1 – Prepare the Area

Clear out the cabinet and have a bucket and some towels ready. You may want to also put down a towel to lie on while checking the pipes. Put the bucket under the pipes. Put the stopper in the sink and run some water in the sink (not too much).

Step 2 – Check the Connections

Unplug the sink and watch the sink trap as the water flows through it. You will be able to see where the leak is. If there is simply a loose connection at a joint, tighten the slip nuts. If you have a metal trap, hand tighten them then use pliers to tighten another half turn. If you have a plastic trap then hand tighten and then use the pliers to tighten another quarter turn. Test the pipe again by running water through it.

Step 3 – Check the Washers

If it is still leaking, loosen the connections and remove the whole trap. Washers may harden or weaken as they age. Take a close look at these rubber washers and install new ones if needed.  

Step 4 – Check for Alignment

If you have a plastic pipe then it may be leaking because the pipes or the connections may be out of alignment. Be sure everything is properly lined up and tightened securely.

Step 5 – Check for Corrosion

Check the pipes to see if there is any corrosion in the pipe that may have caused a leak along the pipe. If you replace a pipe it is a good idea to replace the slip nuts and washers as well.

Step 6 – Get a New Sink Trap

If none of these fix your problem you need to replace the sink trap. Simply loosen the slip nuts with your wrench and remove the entire trap. As with replacing a pipe you will want to put on new slip nuts and washers with the trap since they are inexpensive and may have damage not easy to see with a visual inspection. When you go to purchase the p-trap take the old one with you if necessary to get the correct diameter.

Step 7 – Install the Trap

Insert the new trap. Tighten the connection by hand tightening and then using the pliers to tighten the connection. Be sure not to over tighten a plastic connection, as the plastic can become over-stressed and can crack or break.

Step 8 – Test for Leaks

Run water through the pipes again to be sure that you have no leaks.

That’s all there is to it. You have saved the cost of calling a plumber and you have the satisfaction of having done it yourself.