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How to Fix a Leaking Kitchen Sink

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A leaking kitchen sink can cause water damage, increase your water bill, and create an ideal environment for mold growth. Fortunately, many common sink leaks can be fixed without calling a plumber. This guide will help you identify the source of your leak and provide step-by-step instructions for repairs.

Fixing Drain Leaks

Drain leaks are among the most common kitchen sink problems and typically occur at connection points.

Fixing Drain Leaks

For Sink Drain or P-trap Leaks:

Tools needed: Bucket, adjustable wrench, plumber’s tape, towels

Steps:

  1. Place a bucket beneath the P-trap to catch water
  2. Loosen the slip nuts at both ends of the P-trap by hand or with an adjustable wrench (turn counterclockwise)
  3. Remove the P-trap and inspect for debris, damage, or improper alignment
  4. Check the washers and replace if damaged or worn
  5. Clean all pipe threads and connection points
  6. Apply plumber’s tape to threaded connections
  7. Reassemble the P-trap, hand-tightening the slip nuts
  8. Give the nuts a final quarter-turn with your wrench (avoid over-tightening)
  9. Run water and check for leaks

If the sink drain is leaking where it meets the sink basin:

  1. Loosen and remove the locknut on the underside of the sink
  2. Apply plumber’s putty around the drain flange on top
  3. Reinstall the drain and tighten the locknut from below
  4. Wipe away any excess putty around the drain opening

Repairing Faucet Leaks

Faucet leaks typically stem from worn washers, O-rings, or cartridges.

Repairing Faucet Leaks

For a Leaking Faucet Base:

Tools needed: Screwdriver, adjustable wrench, replacement parts (O-rings or cartridge), plumber’s tape

Steps:

  1. Turn off water supply valves under sink
  2. Open faucet handles to release remaining water
  3. Remove decorative cap on faucet handle (if present)
  4. Unscrew and remove the handle(s)
  5. For cartridge faucets:
    • Remove the retaining nut or clip
    • Pull out the cartridge straight up
    • Replace with identical new cartridge
  6. For compression faucets:
    • Unscrew the stem
    • Replace the washer at the bottom
  7. Check and replace O-rings if worn or damaged
  8. Reassemble in reverse order
  9. Turn water supply back on and test

For Leaking Supply Lines:

Tools needed: Adjustable wrench, plumber’s tape, possibly new supply lines

Steps:

  1. Check if connections are simply loose
  2. Tighten the nuts connecting supply lines to shut-off valves and faucet (clockwise)
  3. If tightening doesn’t work:
    • Unscrew supply lines from both ends
    • Apply new plumber’s tape to male threads
    • Reconnect and hand-tighten
    • Give a final quarter-turn with wrench
  4. If lines are damaged, replace them entirely with new ones

Fixing Sink Rim Leaks

If water is leaking around the edge of your sink where it meets the countertop, the seal has likely failed.

Sink Rim Leaks

Tools needed: Screwdriver, silicone caulk (kitchen/bath grade), caulk removal tool, rubbing alcohol

Steps:

  1. Remove old caulk using a caulk removal tool or utility knife
  2. Clean the area thoroughly with rubbing alcohol and allow to dry completely
  3. Apply a continuous bead of silicone caulk around the sink edge
  4. Smooth the caulk with a wet finger or caulk smoothing tool
  5. Allow to cure completely (typically 24 hours) before using the sink
  6. Avoid running water during the curing period

When to Call a Professional

While many sink leaks can be fixed with basic tools and parts, some situations warrant professional help:

  • Leaks involving the main water line
  • Cracks in the sink basin or drain pipe
  • Corroded pipes that need replacement
  • Leaks that persist despite your repair attempts
  • Water damage to cabinets or countertops
  • Multiple leaks occurring simultaneously

Prevention Tips

Keep your kitchen sink leak-free with these maintenance practices:

  • Avoid overtightening connections (which can crack washers)
  • Don’t hang heavy items from the faucet
  • Avoid pouring grease down the drain
  • Use drain strainers to prevent clogs
  • Check under the sink periodically for early signs of leaks
  • Apply silicone lubricant to faucet parts during repairs
  • Replace worn parts at the first sign of trouble

By correctly identifying the source of your sink leak and following these repair methods, you can fix most common problems yourself, saving money and preventing water damage to your kitchen.

Jennifer Glover
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