How to Repair a Leak Under a Kitchen Sink: Step-by-Step Guide

A leaking kitchen sink can be a homeowner’s nightmare, leading to water damage, mold growth, and a host of other problems if not addressed promptly. Luckily, fixing a leak under the sink can often be a simple DIY project. However, if the task becomes more complicated than expected, you can always rely on Dillon Plumbing to step in and get the job done right.

Follow this step-by-step guide to repair a leak under your kitchen sink, and remember, if things get out of hand, Dillon Plumbing in Nampa, Idaho is just a call away.

Step 1: Identify the Source of the Leak

Before you start the repair, it’s essential to determine the exact location of the leak. Common sources of leaks under the kitchen sink include:

  • The drain pipe
  • The P-trap (the curved section of the pipe)
  • Water supply lines
  • The faucet base or connections
  • Garbage disposal connections

Start by removing any items stored under the sink and use a flashlight to carefully inspect each part of the plumbing. Run the faucet and watch for where water drips or pools.

Step 2: Turn Off the Water Supply

Before performing any repair work, shut off the water supply to prevent further leaking. There are typically two shut-off valves under the sink, one for hot water and one for cold. Turn both valves clockwise to close them. If your sink doesn’t have dedicated shut-off valves, you may need to turn off the main water supply to your home.

Step 3: Tighten Loose Connections

A common cause of leaks under the sink is loose connections between pipes and fittings. Using an adjustable wrench or pliers, tighten any loose nuts or fittings around the water supply lines, P-trap, and drain connections. Be careful not to overtighten, as this could damage the pipes or connections.

  • Pro Tip: After tightening, turn the water back on and check if the leak persists. If so, proceed to the next steps.

Step 4: Replace the P-Trap

If tightening connections doesn’t solve the issue, the next most likely culprit is the P-trap. The P-trap is the U-shaped pipe beneath the sink that prevents sewer gases from entering your home. Over time, it can crack, wear out, or become clogged, leading to leaks.

To replace the P-trap:

  1. Place a bucket under the P-trap to catch any water or debris.
  2. Use pliers or a wrench to loosen and remove the slip nuts on both ends of the P-trap.
  3. Remove the old P-trap and clean any debris or buildup from the surrounding pipes.
  4. Install the new P-trap by fitting it into place and tightening the slip nuts by hand, followed by a slight turn with pliers. Ensure the connection is snug but not overly tight.
  5. Turn the water back on and check for leaks.

Step 5: Repair or Replace a Leaking Drain Pipe

If the leak is coming from the drain pipe rather than the P-trap, it may have cracks or be improperly sealed. To repair or replace the drain pipe:

  1. Disconnect the drain pipe from the sink by loosening the nut where the pipe meets the sink drain.
  2. Inspect the pipe for cracks, worn-out seals, or corrosion. If necessary, replace the drain pipe with a new one.
  3. Install the new drain pipe and tighten the connection. Apply plumber’s tape or pipe thread sealant to the threads to ensure a watertight seal.

Step 6: Check the Water Supply Lines

If the leak originates from the water supply lines, the issue could be due to old or damaged lines, or loose connections.

To fix this:

  1. Inspect both hot and cold water supply lines for signs of wear, cracks, or loose fittings.
  2. Tighten any loose connections or replace the water supply lines if they are damaged.
  3. Use plumber’s tape around the threads of the connections for added security when installing new lines.

Step 7: Test for Leaks

After completing your repairs, turn the water back on and run the faucet. Let the water run for a few minutes to ensure the leak is fixed. Check all connections and pipes carefully to ensure there are no further leaks.

Step 8: Call Dillon Plumbing if the Job Gets Out of Hand

While fixing a leak under the kitchen sink can often be a straightforward task, sometimes complications arise that require professional expertise. If you encounter any of the following issues, it’s time to call Dillon Plumbing:

  • Leaks persist after tightening and replacing parts.
  • You discover more extensive damage to pipes or plumbing fixtures.
  • You’re unsure of the source of the leak.
  • The repair seems too complex or time-consuming.

At Dillon Plumbing, we’re your trusted local plumbing experts in Nampa, Idaho, and we’re here to help with any plumbing issues, big or small. If your DIY attempt isn’t solving the problem, don’t hesitate to reach out for professional assistance. We’ll ensure your kitchen plumbing is back in top shape, so you don’t have to worry about leaks causing damage to your home.