How to Repair a Leaking Sink

Leaking water under the sink can be caused by a number of problems. At Terry’s Plumbing, we encounter leaks under the sink all the time, but find that the reasons behind these problems can be varied. In this post, we’ll cover some of the most common causes of water leakage under the sink and suggest solutions that can help.

Diagnosing the Problem

The first thing to determine is where the leak is coming from. Remove everything from underneath the sink and dry the area out. Try to discover the source of the leak; this can be done by turning the water on to see the seepage, letting the drain backfill somewhat or by leaving a few paper towels underneath the sink to determine the location. Now let’s talk about the places where the sink is leaking.

Where’s the Leak?

Looking under your sink, you’ll see multiple potential sources for a leak.

• Supply Lines – If you have water squirting everywhere, this is probably the kind of water leak you have happening. Though you can sometimes get a slow seeping leak in the supply lines, the pressure in the lines usually makes it travel farther once it has escaped the lines. The lines usually attach from a shut-off valve to the fixture itself.
• Leaks From The Fixture Itself – Though these are not as common as supply line issues, a faucet can begin leaking for a number of reasons. If you’ve had a hard freeze, the power has gone out or you otherwise suspect the fixture itself is dripping, it could be that the valve, cartridge or faucet stem is broken and may need replacing.
• Waste Lines – Your waste line could also be leaking if it has a loosened connection, isn’t vented properly or has a clog further down the line. Unfortunately, waste lines can be a bit of a bother to keep tightened up properly. If you have one that just won’t keep the pipe together, you could consider building a wire harness for holding the entire assembly together. You should also inspect the O ring connection and the threaded nut for cross threading, which can cause damage. 

How Should You Fix it?

Often the source of the leak is a loose connection between a line and a valve. To tighten the connection between a line and a valve, use one wrench to hold the valve and use a second wrench to tighten the compression fitting. If the connection continues to be loose, this could be a sign of dirt or sediment in the pipe around the fitting. To clear out the dirt, turn off the water supply and disconnect the supply line. Clean the fitting with a cloth, line the fitting with Teflon tape, then reattach.

If you determine that the source of the leak is a connection around the drain line P trap, use a wrench to tighten metal fittings or use your hands to tighten plastic fittings. If this doesn’t work, detach the pipes and clean them out. Line the joint with Teflon tape, then reconnect. Water will be trapped in the P trap, so you’ll need a bucket on hand to catch what comes out of the pipe.

Know When to Contact Terry’s Plumbing

If you’ve tried everything suggested above and you haven’t been able to find the source of the leak or fix the leak, this is a good time to get professional help. At Terry’s Plumbing, we help people just like you to maintain their home’s plumbing and avoid costly disasters. If you live in or around Pittsburgh and need help with your plumbing, or if you have a leak you just can’t seem to fix, contact us today. We can help you determine the source of your problem and can also make repairs.