Leaking Kitchen Sink Drain Pipe? Don't Panic - Here's How To Fix It

It can be frustrating and worrying when you discover your kitchen sink's drain pipe is leaking. Water damage under the sink or on surrounding cabinets and floors can happen quickly. While a leaky drain may seem like a plumbing emergency, in many cases the repair is something you can tackle yourself fairly easily.

With a few tools and some basic instruction, you'll be able to stop a drain leak in its tracks and prevent further water damage in the kitchen.

Detecting a Leaky Sink Drain

The first step is identifying that you actually have a leaking pipe under or around the kitchen sink. Here are the most common signs of a drain leak:

• Water pooling on the floor under or around the sink base cabinet
• Wet spots or water stains on the cabinet walls below the sink
• The sound of dripping water when the sink drains
• A musty, damp odor coming from the sink cabinet area

Once you confirm the leak, you'll need to pinpoint exactly where under the sink the water is coming from. Take a flashlight and visually inspect all along the drain pipes and connections for dripping water. Also feel with your fingers along the pipes to detect any moisture.

Locating the Exact Source of the Leak

Finding where the leak originates will inform what repairs need to be made. Here are some methods for tracking down the source:

• Fill the sink with water and trace the path of any dripping water as it travels down the drain
• Look along the horizontal pipe connecting to the vertical drain pipe for wetness
• Check where the drain tailpiece pipe connects to the sink basin
• Remove the p-trap assembly and inspect the slip joints

What's Causing the Leak?

Once the leak source is located, you can diagnose the issue. Common causes of kitchen sink drain leaks include:

• Corroded, cracked, or disconnected pipes and connectors
• Loose slip joints in the pipe connections
• Broken or missing seals around the sink drain basket
• A clogged drain causing water to force its way out of pipe joints

Fixing a Leaky Sink Drain Connection

Often a leaky joint, worn seal, or loose pipe is the culprit. Luckily these are easy fixes. Here's how to tackle common kitchen sink drain connection leaks:

Tightening Loose Slip Joints

Many connections under the kitchen sink use a slip joint, which has a ring that tightens to seal the joint. Over time these can loosen due to vibrations from the garbage disposal or sink use. To stop a leak:

• Loosen the slip nut at the leaky joint using slip joint pliers or a wrench
• Apply plumber's tape or pipe joint compound to the threads
• Hand tighten the slip nut first, then use the pliers to tighten an additional quarter turn

Be careful not to overtighten, as this can crack the nut or pipe. The slip nut just needs to be snug enough to compress the beveled pipe collar and create a watertight seal.

Replacing Faulty Drain Seals

Leaks also occur if the plumber's putty around the sink drain basket decays. To fix this:

• Use putty knife to scrape away all the old putty from the drain flange
• Apply new plumber's putty around the flange, place the basket in the sink, and tighten the mounting nut

You may also need to replace rubber gaskets within compression fittings on PVC, ABS, or metal pipe connections. Match the new gasket to the pipe size.

Installing New Pipes and Connectors

For pipes or fittings that are severely corroded or cracked, replacement is necessary. The process is:

• Cut out the damaged section of pipe with a hacksaw
• Use couplings and unions to join new pipe pieces
• Make sure slopes allow water drainage

Use tube cutters for tight spaces. Having extra connectors and pipe pieces on hand is useful for kitchen sink plumbing repairs.

Unclogging a Blocked Drain

If the drain leak corresponds with a clogged drain, try:

• A zip-it tool to grab hair clogs
• A drain snake to clear deep clogs
• Baking soda and vinegar to break up gunk

You may need to detach the p-trap and physically remove a stubborn clog. Eliminating the clog can stop water from leaking out of pipe joints.

Replacing or Repairing a Leaky P-Trap

The p-trap is particularly prone to leaks. This u-shaped piece of pipe holds water to prevent sewer gas from entering the sink drain. Signs of a leaky p-trap include:

• Water dripping from the trap's slip nut connections
• Wetness along the trap arm pipe joint

Fixing a Defective P-Trap

Try these p-trap repairs before fully replacing it:

• Tighten the slip nut connections with pliers
• Cut out a rusted or cracked section of trap and replace with new pipe

Use a bucket to catch water when removing the trap. P-traps mostly twist off by hand, but pliers may help loosen stubborn connections.

Unclogging a Blocked P-Trap

To clear a clogged p-trap:

• Detach from the sink drain and remove any debris
• Snake the trap arm pipe in case the clog is further down

Reassemble the p-trap, ensuring the bottom of the u-bend is roughly 2 inches lower than the drain pipe outlet to hold water.

Installing a New P-Trap

For a complete p-trap replacement:

• Measure and cut new pipe pieces to size
• Attach pipes with slip joints and position the u-bend properly

Getting the trap arm positioned correctly with proper slope takes patience. Having an extra set of hands is useful here.

When to Call a Professional Plumber

While many kitchen sink drain leaks are DIY-friendly fixes, call a pro if:

• The leak requires access to pipes in the wall or under the floor
• Cast iron pipes need replacement
• You're uncomfortable doing the repairs yourself

A professional plumber has the expertise to fully diagnose the leak issue and equipment to fix problems in tight spaces or with tricky plumbing systems. They can also advise if a full drain pipe replacement is needed.

Detecting and repairing a leaky kitchen sink drain pipe is much easier than it may initially seem. In an hour or two, you can likely diagnose the leak source yourself and complete a fix with basic tools and supplies.

Acting quickly to stop a drain leak prevents further water damage under and around the sink. Keep an eye out for the signs, like water on the floor or dripping from pipe joints. And don't panic - take control of the situation using this guide to understand sink drain leaks and make the needed repairs.