Why Is Your Sink Leaking? Top Causes & Fixes

Emily Jul 26, 2026

A leaky sink can be quite a nuisance, causing wet patches, unpleasant smells, and increased water bills. To fix the issue, it's crucial to identify the cause first. This guide explores the common reasons behind a leaking sink and provides solutions to help you tackle the problem.

Fix Water Leak Under Kitchen Sink
Fix Water Leak Under Kitchen Sink

Understanding the different components of your sink can help you pinpoint the source of the leak. In this article, we'll delve into four primary causes and their signs, along with troubleshooting steps for each.

How to Fix a Leak Under The Kitchen Sink?
How to Fix a Leak Under The Kitchen Sink?

Faulty Faucet

A faulty faucet is often the culprit behind a leaky sink. Over time, the internal parts of the faucet can wear out, leading to dripping water.

the parts of a water heater
the parts of a water heater

Two of the most common causes of faucet leaks are worn-out seals and damaged O-rings.

Worn-out Seals

Water supply leak under kitchen sink
Water supply leak under kitchen sink

Seals help maintain a watertight connection in your faucet. When they become worn out or damaged, water can escape, causing leaks.

To fix this issue, you may need to replace the seals. Shut off the water supply and disassemble the faucet to access the seals. If you're unsure about the process, consider hiring a professional plumber.

Damaged O-rings

a water faucet that is leaking from it's spout and has the words serpro on it
a water faucet that is leaking from it's spout and has the words serpro on it

O-rings act as waterproof barriers in your faucet's valve seat. If the O-ring gets damaged or broken, water can seep through and cause leaks.

To resolve this issue, you'll need to replace the damaged O-ring. Similar to sealing repair, locate the O-ring in your faucet's components and replace it carefully. Again, if you're not comfortable doing this yourself, contact a local plumber for assistance.

Corroded Plumbing Pipes

Why Is There Water Under Sink But No Leak? (POSSIBLE Causes)
Why Is There Water Under Sink But No Leak? (POSSIBLE Causes)

Another common cause of sink leaks is damaged or rusted plumbing pipes. While not immediately visible, leaks from pipes can cause significant water damage over time.

Here are two scenarios to look out for when dealing with pipes:

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Rusted Pipe Pipes

Over time, exposure to moisture can cause pipes to rust and corrode, eventually leading to leaks. If you suspect this is the case, look for signs of rust around the pipes, such as red or orange streaks.

Replacing the affected pipes is the best solution in this case. If you're not comfortable doing this yourself, it's recommended to hire a professional plumber to ensure the job is done right.

Leaky Pipe Joints

Pipe joints are another vulnerable area where leaks can occur. Joints can deteriorate over time, allowing water to escape and causing leaks.

To fix leaky pipe joints, you may need to tighten them or replace the affected section. If the problem persists, it's best to consult a professional plumber to avoid further water damage.

Worn-out Sink Components

Sometimes, leaks can occur due to worn-out or damaged sink components. Two common areas to inspect are the drain assembly and the sink's shut-off valves.

Damaged Drain Assembly

The drain assembly, consisting of a strainer basket, drain collar, and putty, can become loose or damaged over time, leading to leaks.

To fix this issue, you'll need to replace the damaged drain assembly. First, clear the drain of any debris, then remove the damaged components. Next, apply new plumber's putty, attach the new drain assembly, and tighten everything back into place.

Faulty Shut-off Valves

Shut-off valves control the water supply to your sink. If these valves become faulty or damaged, water can leak even when the faucet is turned off.

To troubleshoot this issue, turn off the main water supply to your home and attempt to open and close the valve. If it's stiff or won't close completely, it's probably faulty and needs replacement. As with other repairs, if you're not confident in your plumbing skills, consider hiring a professional.

Loose or Cracked Sink Basin

In some cases, a leaky sink can be attributed to a loose or cracked basin. This can occur due to improper installation or settling of the home's foundation.

To address this issue, you'll need to tighten the sink basin or, in the case of cracks, replace it entirely. For minor cracks, you can use epoxy to seal the affected area. However, if the basin is severely cracked or damaged, it's best to replace it with a new one.

Lastly, routine maintenance can help prevent many of these issues from occurring. Regularly inspect your sink and plumbing for any signs of wear or damage, and address them promptly to save yourself from costly repairs down the line. If you're not comfortable tackling these repairs yourself, remember that professional plumbers are always available to help.