Is Your Bathroom Sink Leaking? Here’s How to Fix it! 

By: Diana Rodriguez-Zaba
Updated on: March 26, 2024

Is your bathroom sink leaking underneath? Perhaps you’ve noticed pooling water on the floor or inside your cabinets. If so, you need to act fast!

Fortunately, we’re here to help.

As one of the leading water damage restoration companies in Chicago, we’ve helped hundreds of homeowners deal with leaky bathroom sinks and clean up the water damage they create.

In this blog, we’ll share our top tips for repairing a leaking bathroom sink and getting life back to normal as quickly as possible. 

Let’s dive in. 

Why is My Bathroom Sink Leaking Underneath?

sink leaking underneath

Bathroom sinks leak for a variety of reasons.

Common causes include faulty or loose pipe connections, broken drain pipes, or drain flanges that leak, causing the bathroom faucet to leak underneath the sink and damaging the vanity, floor, or ceiling – if your bathroom is on the second floor. 

Blocked water supply lines, broken or faulty p-traps, and poor connections between the sink and the drainpipe can also cause sink leaks.  

The good news about all these things is that they’re fixable – you just have to diagnose them first. A leaky bathroom sink can often be fixed by tightening drain connections or replacing worn-out fittings. 

To help you diagnose which part of your sink is leaking, we’ll provide a comprehensive breakdown of your sink’s different components in the next section. 

11 Main Parts of Your Sink 

Here are the main components you’ll find in virtually every bathroom sink:

1. The faucet

The faucet is the part of the sink that you use the most.

Turning it on allows water to flow out. While sink faucets seem simple, they rely on waterspouts, controls, aerators, flanges, gaskets, and a handful of screws to do their jobs, and a problem with any of these components could cause a leak. 

2. Controls

The controls are the part of the faucet where you activate water flow.

Some controls are a single-lever type that you rotate to adjust the water temperature; others have separate hot and cold controls on the left and right, respectively.

3. The basin

The basin is the part of the sink that collects water.

Plugging the basin drain allows you to fill the sink with water while unplugging the drain sends the water flowing into your sink’s pipes. 

4. Drain

The sink’s drain separates the basin from the p-trap and plumbing connections, usually hidden within your walls or inside your bathroom vanity.

5. Tailpiece

The drain tailpiece is the part of your sink’s piping that connects the drain fitting to the rest of your sink’s plumbing.

It works by running water away from the sink. 

6. Water supply lines

The water supply lines run from the wall to the sink, attaching to the faucet controls.

They supply both hot and cold water. 

7. The P-Trap

The p-trap allows water to pass through the pipes beneath your sink but features a bend in the pipe, which keeps sewer gas from traveling up your lines.

8. Stoppers

A stopper is a drain with a fitting that allows the drain to be lifted and lowered easily.

9. Gaskets and nuts

Components like the rubber gasket, friction gasket, and strainer nut work together to connect the strainer flange and p-trap and create a watertight seal. 

10. The shut-off valve

Shut-off valves look like oval-shaped handles and are usually flush with the wall on most bathroom sinks.

They control water supply lines and allow you to stop or regulate water flow to the sink.

11. Cleanout

The cleanout is a type of pipe fitting that makes it possible to get rid of clogs that collect near the p-trap. 

How to Fix a Leaking Bathroom Sink

The way you fix your leaking bathroom sink depends on where the leak is coming from.

Here’s some guidance for different types of leaks:

Leaks From the Water Hose

The first step to fixing a leak from the water hose is to double-check all pipes and supply lines.

Tighten leaking or loose connections with pliers.

Remove the hose and check the internal gasket if that doesn’t stop the leak. If it is worn, replace it. 

Leaks From the P-Trap

The p-trap is the curved pipe that sits beneath your drain. Most modern p-traps are held together with a nut that connects them to the sink pipe.

To fix a leaking p-trap, tighten the slip nut with a hand tool. If that doesn’t stop the leak, use a pipe wrench, adjustable wrench, or a pair of plumbing pliers to tighten the nut.

Leaks From the Shut-Off Valve

Sometimes, shut-off valves leak because they’re worn out. Turn off the main water supply and evaluate the valve in these instances. If the shut-off valve is soldered on, you’ll need to hire a plumber to replace it. 

Leaks From the Sink’s Drain

Leaks that involve your sink’s drain assembly can be challenging to repair and often require the help of a plumber.

If you’d like to DIY the job, you can usually do it by removing the p-trap, wrapping the drain threads in plumber’s tape, and replacing both the p-trap and drain. 

Leaks at the Connections

Leaks usually occur at sink connections simply because the connections are loose.

To fix them, use pliers to tighten any loose connections and replace worn-out hardware. 

Leaks From the Handle

A leaking handle may mean it’s time for a replacement.

Purchase a new handle at your local home goods or hardware store and follow manufacturer instructions to swap out your old one. 

How to Deal with the Water Damage

sink water damage cleanup

If a bathroom sink is leaking underneath, it’s causing water damage with every drip. Once you’ve stopped the leak, you’ll also need to repair the water damage. 

While a little bit of water damage may not seem like a big deal, it can wreak havoc on your bathroom.

The reason is simple: most bathroom leaks are hidden beneath flooring or behind vanities, so they go unnoticed for a long time.

Over time, the water damage builds up, increasing your bathroom’s humidity and causing potential mold growth

Once it forms, mold can cause various adverse health consequences for vulnerable populations, including children, people with allergies, and older adults. Mold also makes your bathroom smell damp and musty. 

Because of this, total water damage repair is a necessity. If you’ve discovered a water leak in your bathroom, contact a water damage restoration company to evaluate the damage and repair any rotted wood, mold, or other damage that may be present. 

If you’re in the Chicago area, contact ServiceMaster by Zaba and we’ll take care of the cleanup and repair all damages: (773) 647-1985

How to Prevent Leaking Bathroom Sinks

The best way to prevent leaking bathroom sinks is to routinely inspect and repair your sink. Replacing aging components before they wear out entirely allows you to stop leaks in their tracks and prevent the water damage they cause. 

Additionally, be sure to check your home’s water pressure regularly. 

Ideal home water pressure is between 40-60 psi. Water pressure higher than that can cause broken or burst pipes, leading to a leak. 

To check for leaks, consider placing a few pieces of paper towel in your bathroom vanity, beneath your sink’s pipe fittings. Check the paper towels regularly for signs of water stains or dampness, which could indicate the presence of a new leak. 

Dealing with a Leaking Bathroom Sink in Chicago? We Can Help!

You don’t have to live with a leaky sink forever! Contact the team at ServiceMaster Restoration by Zaba for professional plumbing leak cleanup you can trust.

As a team of leading restoration experts, we understand how to diagnose and pinpoint sink leaks and repair the water damage they create.

Contact us today to request service or to learn more about our team and how we can help you: (773) 647-1985

How much does it cost to repair a leaking bathroom sink?

The cost to repair your leaking bathroom sink will depend on a few factors, including the cause of the leak, the extent of the water damage, and what kind of replacement parts your sink requires. 

Are leaks covered by homeowners’ insurance?

Most homeowners insurance policies cover water damage that is “sudden and accidental,” like burst pipes. Your policy might not cover gradual damage from a leaking bathroom sink or a faulty appliance, though, so it’s essential to stop these problems in their tracks.

What causes a dripping bathroom sink?

A dripping bathroom sink is annoying, but it can also be a big deal for your home. Usually, dripping sink faucets are caused by defective O-rings, washers, gaskets, or other parts. If these parts aren’t replaced quickly, the slow drip can lead to water damage that impacts your home’s drywall, flooring, or vanity under your sink.