Leaky Kitchen Sink? Here's How To Easily Diagnose and Repair It Yourself

A leaking kitchen sink can quickly become a soggy, smelly nuisance. Left unchecked, water seeping from supply lines or drain pipes leads to ugly water stains, potential mold growth, and possible damage to cabinets and floors. But many common leaks under a kitchen sink often stem from minor issues you can tackle yourself.

With a few basic tools and some plumbing know-how, you can solve pesky leaky sink issues, prevent ongoing water damage, and save the expense of calling a plumber.

Signs Your Kitchen Sink is Leaking

Catching a leak early provides the best chance for quick and easy repairs. Be on the lookout for these common indicators of a sink leak:

• Water pooling under the sink or dripping onto the floor
• Visible water damage on cabinet walls and baseboards
• A musty, damp smell coming from the cabinet area
• The faint sound of dripping when the sink is being used or not in use

Don't ignore puddles or running water in the cabinet area. Address any signs of a leak promptly to mitigate water damage.

What's Causing the Leak Under Your Sink?

Before attempting repairs, it's important to determine the specific source of the leak. Different culprits require different solutions. Here are some of the most common causes of leaks under a kitchen sink.

Drain Pipes

The drain pipes carry wastewater downward from the sink to eventually connect with the main sewer line. Clogs or cracks within these pipes can force water to back up and seep out into the cabinet.

Supply Lines

Supply lines deliver fresh water to the sink faucet and accessories like a sprayer or soap dispenser. Leaks here may be due to worn out washers or gaskets, loose fittings, or corrosion and rust eroding the pipes.

P-Trap

This curved section of pipe underneath the sink serves to hold water and prevent unpleasant sewer gases from entering through the drain. A detached or cracked p-trap allows water to leak before entering the main drain pipe.

Garbage Disposal

A leaking garbage disposal can result in water pooling at the base, typically due to worn seals or mounting connections that have loosened over time.

How to Pinpoint the Exact Source of the Leak

Finding the specific spot the water is coming from is crucial for proper repairs. Follow these steps to sleuth out the leak source:

• Thoroughly wipe and clean the cabinet area and allow the sink to completely drain.
• Run water into the sink from the faucet and garbage disposal while inspecting all pipes and connections for any drips.
• Pour a few drops of food coloring or water dyed with ink down the drain to isolate cracks in sections of drain pipe.
• Check around the p-trap area for temperature changes that signal water backing up due to a clog.
• Examine the supply line connections for any beads of water or moisture around joints.
• Look for specific water stains or damage spots that pinpoint the leak site.

DIY Fixes for Common Kitchen Sink Leaks

Once you've determined the culprit, roll up your sleeves to make the repair. Here are tips for resolving some of the most frequent under sink leaks:

Tightening Loose Connections

Detached drain pipes or supply lines are easy DIY fixes:

1. Turn off the hot and cold water supply valves.
2. Check connections on supply lines, the drain tailpiece, disposal, and p-trap.
3. Hand tighten any loose slip nuts, couplings, screws or bolts.
4. Use tongue-and-groove pliers to firmly tighten leaky compression fittings or nuts.

Replacing Worn Washers and Gaskets

When supply line connections drip steadily, replacing the worn washers or gaskets typically solves the problem. Follow these steps:

1. Turn off water supply and disconnect the leaky line.
2. Unscrew the fitting and remove the worn washer/gasket.
3. Insert a new washer or gasket of the same size.
4. Re-attach the supply line and turn water back on to test for leaks.

Clearing Clogged Drains

For a kitchen sink that's slow to drain, a clogged pipe may be forcing water to back up. Try this to clear blockages:

• Remove the p-trap and use a wire coat hanger or zip-it tool to fish out debris.
• Flush the pipe with very hot water to dissolve built-up grease and grime.
• Use a plumber's snake to reach and dislodge clogs further down the line.

Replacing Corroded or Damaged Pipes

For pipes that are corroded, badly cracked, or detached, replacement is the best solution:

1. Measure and purchase new pipes of the correct size and shape.
2. Cut new pipes to the needed length and lightly sand cut edges smooth.
3. Attach appropriate fittings using thread tape to avoid leaks.
4. Securely connect new pipes into place without overtightening.

Call a Pro for Tricky Leak Repairs

While many kitchen sink leaks can be repaired DIY, it's best to call a professional plumber if:

• You can't diagnose the exact source of the leak.
• Pipes show severe corrosion or cracks.
• The leak returns soon after your repair attempt.

For complex diagnosing or access needed to internal plumbing walls, a licensed pro has the skills to remedy the leak. Leaky pipes left unaddressed lead to soggy cabinets, mold growth, and water ruining subfloors.

Once you notice water under your kitchen sink, take quick action by inspecting for the source. Addressing minor leaks from supply lines, slip joints or clogged drains is very doable for DIYers. With a few common tools and proper technique, you can eliminate the leak, prevent ongoing water damage, and avoid calling an expensive plumber.