Quick Answer:
If you see seepage at the gasket area the gasket is likely compressed, torn, or contaminated. Start by turning off power and inspecting the gasket surfaces and mating areas. In many cases cleaning the surfaces and replacing the worn gasket with the correct replacement seal stops the leak quickly.
Why This Happens
The gasket between a sink and a disposal sits under constant stress: weight of the unit, water, heat, and occasional cleaning chemicals. Over time the rubber or neoprene can flatten, crack, or pick up grit. Misalignment, debris, or a warped sink surface can prevent a tight seal and let water seep out. Regular use and older installations are the most common causes.
Step-by-Step What to Do
1. Turn off power and prepare the area
- Switch off the disposal at the wall, then cut power at the circuit breaker or unplug the unit to be sure it cannot start while you work.
- Place a bucket under the sink to catch any water and clear out items from under the sink for room to work.
2. Remove the disposal or tailpiece enough to access the gasket
- Support the disposal’s weight. If your model hangs from a mounting ring, hold the unit while you loosen the mounting tabs. If it’s heavy or awkward, have a helper assist or use a support strap.
- Loosen the drain trap connections if needed to give yourself clearance.
3. Inspect the gasket
- Look closely at the sink-side and disposal-side sealing surfaces. Inspect gasket surfaces for flattening, tears, or debris preventing a tight seal. Also check for grit, old putty, or mineral buildup where the gasket sits.
- A distorted, compressed, or torn gasket should be replaced rather than reused.
4. Clean mating surfaces
- Wipe both the sink flange and the disposal flange clean with a rag and mild cleaner. Remove old plumber’s putty, crusted deposits, or loose debris that could keep the gasket from seating.
- Dry the area completely before installing a new seal.
5. Fit the correct replacement gasket
- Buy the gasket or seal set specified by the disposal or sink manufacturer. Fit it exactly as the instructions show—some gaskets have orientation or a lip that must face a certain way.
- When reinstalling, align the flanges and tighten mounting hardware evenly so the gasket compresses uniformly.
6. Reassemble and test
- Reattach the trap and any other plumbing. Restore power and run water while checking for leaks. Observe for a few minutes while the unit and plumbing cycle through normal use.
- If a small drip continues, tighten evenly a bit more; persistent seepage usually means the gasket or a mating surface is still compromised.
If the leak starts after reassembly and you recently changed other parts, check related installations such as Leak after replacing sink or Leak after replacing disposal for troubleshooting steps.
What Not to Do
- Do not stack mismatched gaskets or mix parts from different kits; use the correct seal set.
- Do not overtighten mounting screws or bolts to hide a bad seal—uneven pressure can make leaks worse or crack parts.
- Do not assume a little putty or tape will cure a badly deteriorated gasket; a worn seal should be replaced.
When to Call a Professional
- You’ve replaced the gasket and cleaned surfaces but the leak continues or shifts location.
- The sink flange or disposal mounting is corroded, cracked, or the sink itself is warped or damaged.
- Access is limited, or the work requires electrical disconnection beyond your comfort level.
Safety Notes
- Always cut power at the breaker and verify the unit cannot start before working on or under a disposal.
- Use gloves to protect hands from sharp edges and old grime. Eye protection is sensible if you’re scraping deposits.
- Support the disposal when loosening the mounting ring; dropping the unit can cause injury or further damage.
Common Homeowner Questions
- How often should the gasket be replaced? — Replace when it shows visible wear, compression, or leaks; there’s no fixed interval but many last several years.
- Can I use silicone or plumber’s putty instead of a gasket? — No, those are not reliable substitutes for a manufacturer-specified gasket and can cause leaks or interfere with fit.
- Will tightening the mounting ring always stop a leak? — Not always. Tightening helps only if the gasket is intact and surfaces are clean and flat; a damaged gasket must be replaced.