Fixing a Leaking Sink Drain

Leaking plumbing is never fun to deal with, but at least when a drain leaks, the water is not pressurized like with a water line leak.

I recently discovered a slow leak from one of the two drains in our kitchen sink. Unfortunately, this was a drain I installed seven months ago, so I was fixing a problem I created. Ah, such is the life of a do-it-yourself person!

Find the Leak
The first step in fixing a leaking drain is determining where the leak is coming from. This may not always be as simple as finding the water droplets, because the droplets of water can travel far from the leak location before they fall to the ground. Keep in mind that water obeys the law of gravity, so if you follow a water trail up to its highest point, that will usually be the source of the leak.

The blue arrow in this photo shows where some water was collecting. The PVC pipe above was also wet. The pipes and drain to the left were completely dry, so I knew they were not the culprit. After using a flashlight, I could see that the drain itself was leaking, not the pipes.

Fixing a Leaking Sink Drain
Now that I knew what part of the drainage system under the sink was leaking, it was only a matter of fixing it before it got any worse.

Luckily for me, this was a quick fix. I would only need three things:

1. Plumber's Putty
2. Teflon (Plumber's) Tape
3. Channel Lock Pliers

1. Place a large bowl or small bucket under the pipes to catch any water.
2. In order to remove the drain, I had to first unscrew the first connector (first photo).
3. Then, I removed the 'T' section of PVC pipe (second photo).
This 'T' section has a splash shield in it that prevents water coming from the left arm to splash up and out of the top opening. When reinstalling, make sure it is installed correctly.

At this time, I took the 'T' section outside and used our garden hose to flush it out and clean it. This step is not necessary, but I figured that I might as well do it while I can.

4. I now had access to the drain. The drain is attached to the bottom of the sink by a large nut. Between the nut and sink is a washer. Unscrew the large nut and place the nut and washer off to the side.

5. The drain is now free, all that has to be done is to lift it out of the sink. The plumber's putty may offer a little resistance, so if you are having trouble, try twisting the drain a little to break the putty's hold.

I have seen some people use silicone adhesive caulk instead of plumber's putty.
The silicone caulk will ensure the drain is water proof and secure, but once it adheres, you will not be able to remove the drain. This would be especially bad if your sink is like ours and is made out of solid surface material because it can lead to a cracked sink.

6. Remove all traces of old plumber's putty from both the sink and the drain. The old putty may be reused if it has not hardened.

7. Apply a bead of plumber's putty around the collar of the drain. There should be enough putty to make a good seal. When you install the drain, some putty should be squeezed out, if not, there is not enough putty.

8. Reinstall the large washer and the drain nut. Tighten. I then used a rag to clean all traces of putty in the sink. A good way to judge whether you have enough putty and the drain is tight enough is by looking at how flush the collar of the drain is to the bottom of the sink. If the collar sticks out past the bottom of the sink, then there is either too much putty or the drain has not been tightened down enough.

9. Wrap the threads of the sink drain and all the threaded portions of the PVC pipe with new Teflon tape (clean the old tape out first).

10. Reinstall the 'T' section of pipe and tighten all the fittings. That is it!