Fix a Leaky Sink Gasket: Step-by-Step Guide

Quick answer

To fix a leaky sink gasket, turn off the water supply, remove the old gasket, and install a new one. Ensure the sink and drain are clean before reassembling. Check for tightness but avoid over-tightening.

Confirm the symptom

• Water leaks around the sink base or under the sink cabinet
• Dripping from the drain area when the faucet is off
• Standing water near the sink or floor after use

Tools and prep

• Adjustable wrench
• Plumber's putty or silicone sealant
• Replacement sink gasket
• Bucket or towel to catch water
• Turn off water supply before starting
• Protective gloves and safety glasses

Step-by-step troubleshooting

1. Turn Off Water Supply
   Do: Locate and turn off the shut-off valves under the sink.
   Observe: Water stops flowing from the faucet.
   Means: Water is safely off for repair.
   Next: Prepare the sink area
2. Prepare the Sink Area
   Do: Place a bucket under the sink to catch any residual water and disconnect the P-trap if necessary.
   Observe: No water drips from the drain during the process.
   Means: Area is ready for gasket removal.
   Next: Remove old gasket
3. Remove Old Gasket
   Do: Use an adjustable wrench to loosen the nuts securing the drain assembly.
   Observe: Drain assembly loosens and can be lifted out.
   Means: Old gasket is accessible for removal.
   Next: Clean the area
4. Clean the Area
   Do: Scrape off old gasket material and clean the sink flange and drain base with a cloth or brush.
   Observe: Surface is clean and free of debris.
   Means: Ensures proper seating for the new gasket.
   Next: Install new gasket
5. Install New Gasket
   Do: Place the new gasket over the drain flange and align it with the sink opening.
   Observe: Gasket fits snugly without twisting.
   Means: Proper alignment prevents leaks.
   Next: Reassemble the drain
6. Reassemble the Drain
   Do: Reattach the drain assembly and tighten the nuts by hand first, then slightly with a wrench.
   Observe: Drain is secure but not over-tightened.
   Means: Gasket is compressed properly without damage.
   Next: Test for leaks
7. Test for Leaks
   Do: Turn the water supply back on and run water through the sink.
   Observe: No water leaks from the drain or base.
   Means: Repair is successful.
   Next: Final check

Common causes

Parts matching

Choose the right sink gasket for your repair:

• Measure the diameter of the drain opening and flange to ensure a proper fit
• Select a gasket made of durable rubber or silicone for long-term use
• Check if your sink requires a flat, beveled, or raised gasket based on the drain design
• Match the gasket thickness to the space between the sink and drain
• Consider a reinforced gasket for heavy-use sinks or commercial-grade fixtures

If unsure, take the old gasket to the hardware store to find an exact match.

When to call a professional

• Leaks persist after replacing the gasket
• The sink flange is damaged and needs replacement
• You cannot locate or access the water shut-off valves
• The drain assembly is corroded or stuck and won't budge
• You're uncomfortable working with plumbing tools or under the sink area

FAQ

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