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Sink Leakage? Here’s What to Do

Sink Leakage? Here’s What to Do

If you have sink leakage, there are a few steps you need to take. First, you need to check the source. Then, you need to address it to prevent future damage from occurring. Read on to learn more.


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What Is Sink Leakage?

Opening your cabinet to find a puddle or steady stream of water under the sink is every homeowner’s nightmare. You know there’s a leak somewhere, but have no idea how to pinpoint its location or determine how to fix the leak.

It can be overwhelming because a bathroom or kitchen sink could leak for a number of reasons. However, the most common reasons for sink leakage can often be fixed easily, usually within a few minutes.

Troubled Woman Looking At Leaking Sink Pipe In Kitchen as an image for a piece on sink leakage

Andrey_Popov/Shutterstock

Here are some of the most common reasons for sink leakage and steps you can take to diagnose and fix your leak on your own. Some issues might require you to call a plumber, but you may be able take care of all or part of the plumbing repair job yourself and save money.

If you know or think you might have a leak under your kitchen or bathroom sink, you’ve got to take action quickly. Water leaks not only increase your water bill, but the standing water also creates the perfect environment for mold and mildew to thrive.

And those can cause dangerous health problems. To avoid this, keep reading to learn the most common reasons for leaky sinks and how you can easily fix the issue.

Common Reasons for Sink Leakage

  • Faucet–You’ll recognize a faucet leak because it happens in plain sight. Water may seep out and collect around the faucet when the water is running. Or it may run under the counter where it can’t be seen as easily. Worn out gaskets and washers are usually the culprit. But even a full faucet replacement is an easy task to do yourself.
  • Water supply–You’ll know if the water supply to your sink is the issue if there is a leak around the shut-off valves. If water appears to be leaking from the shut-off valves, the most common reason is that the compression nut fittings have come loose and must be tightened. This is an easy DIY fix.
  • Drain–A leak in the sink drain area is usually due to blockages, loose connections, or corrosion. Drain leaks range from an easy fix–hand-tightening nuts, for example–to more complicated processes that include replacing entire sections of the drain. Some drain leaks are easy DIY fixes.
  • Other–From small gasket or o-ring leaks and deteriorating caulk to big leaks that are nearly impossible to detect, if a link doesn’t originate from the water supply or drain, you’ll probably want to have a plumber come look at it. Some of these plumbing leaks are easy DIY fixes, but others require some expertise.

Faucet Leaks

The water faucet delivers the water from your water supply line into your sink. Damaged or old washers, o-rings, or gaskets are often the cause of a leaky faucet.

An o-ring that doesn’t fit properly or is damaged can’t do its job of helping seal a water valve. If the o-ring is your problem, the leak will appear under your sink faucet handle. You can easily replace the o-ring to resolve the issue.

A faucet that drips even when it’s off is a tell-tale sign of a problem with your seat washer. It may be loose or worn and in need of replacement. You can pick up these replacements at your local home improvement store.

As an image for a piece on sink leakage, Water drop from chrome faucet and water pipeline background. Wash Basin ceramic tile at bathroom. Drink water plumbing pipeline. Resource conserve concept.

Charcompix/Shutterstock

If water is leaking from the base of the faucet, it’s likely that the two o-rings within the spout are at fault. If your faucet spout is older, it can become irregularly shaped and fail to create a good seal with the o-rings.

In this case, the entire faucet needs to be replaced. If not, simply replacing those two o-rings (and rubbing plumbers grease on the o-rings before installing) will take care of the problem. By skipping this step, your sink leakage will continue to happen.

If these fixes don’t resolve the faucet leak, it could be a corroded valve seat or faulty compression mechanisms inside your faucet. In any of these cases, you will need to replace the entire faucet unit.

Water Supply Leaks

Water comes to your sink faucet through the water supply line. If there’s a leak here, it will be a steady, constant drip. Test for leaks by using a paper towel and blotting along the supply line where you think the leak is.

Mark the line at the leak once you locate it. Water supply line leaks can happen for a few reasons. The lines may need a better, tighter connection. The lines may need to be replaced entirely.

You might need to replace the water shut-off valve. These can be difficult fixes for the average DIYer. Personally, I leave that to the plumber, as I’m not 100% confident in my abilities. Prudent homeowners know when to call in the pro.

Drain Leaks

Leaks in the drain line may not be steady or constant like those from a water supply line. One of the most common reasons for drain line leaks are nuts that aren’t properly tightened.

If you can feel that it’s loose and know that’s causing your leak, simply re-tighten the nut on the drain pipe with a wrench or pliers until it’s snug. Another cause of drain line leaks are over-tightened nuts.

Closeup of a sink S Trap made of white PVC plastic with a broken connection and water pouring out. Square format over a gray background.

Steve Cukrov/Shutterstock

Over-tightening compresses the rubber gasket or sealing washer under the nut until water is able to escape and leak out. In this case, you might need to replace the gasket or seal the washer.

If you’ve tried these fixes and still have the leak, something is going on deeper in the drain or isn’t visible with the setup intact. It could be a problem within the drain pipe and/or drain outlet flange. That problem could be visible to you as:

  • Cracks or holes
  • Stripped plastic or metal threads
  • Damaged/old gaskets and sealing washers
  • Damaged drain outlet flange or drain pipe
  • Damaged nut

A plumber will be able to quickly determine what is causing the sink leakage and correct the problem with either replacement parts or by using Plumber’s Tape and Plumber’s Putty.

Other Leaks

If you know that your leak isn’t from the faucet, water supply line, drain pipe, or drain outlet flange, there are still a range of issues causing it. Your best diagnostic tool is a flashlight under your sink.

Look for any swollen or water damaged wood or particle board under the sink. That will point you in the direction of your leak. One common problem is leaking between the countertop and the sink itself.

Test to see if this is the issue by pouring a little water around the edges of your sink, then checking underneath to see if the water makes its way under the cabinet. If you see water under the sink after this test, try:

  • Tighten the nuts that secure the sink base under the counter
  • Remove old caulk and re-caulk these areas to create a fresh, waterproof seal

When to Call a Plumber

If your leak isn’t fixed by a simple tightening of a nut or replacement of a rubber gasket, it may be time to call a professional plumber to take care of the leak.

Although it can be overwhelming to tackle a plumbing problem on your own, dealing with a leaky sink is a great way to familiarize yourself with your plumbing. It’ll also help you hone your ability to fix small household problems yourself.

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Can You Fix Sink Leakage?

Don’t let standing water or steady leaks result in damage to your kitchen or bathroom. Take these steps to diagnose and repair the leak. If the problem is more than you can handle, don’t hesitate to call a plumber to make sure the job is done properly.

If you liked our guide on sink leakage, let us know by rating our article. And while you’re here, make sure to check out our other complete guides to whip your home into shape.

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