Symptoms
- Leak started right after installing a new disposal
- Water drips from the sink flange, mounting ring, or a fitting
- Leak may only show up when running water or the dishwasher
- No leak was present with the old unit
Likely causes
- CommonInsufficient or missing plumber's putty at the sink flangeThe seal between the sink and flange needs a full, even rope of putty.
- CommonMounting ring not fully locked into placeThe disposal must twist-lock fully; a partial lock leaves gaps.
- CommonDishwasher hose or discharge tube not tightened or seatedNew connections need firm, even tightening without overtightening plastic threads.
- PossibleDischarge tube gasket missing or pinchedThe gasket between the disposal outlet and drain trap can be forgotten or seat crooked.
What to do
- Turn off the disposal and dry all surfaces around the flange, mounting ring, dishwasher inlet, and discharge outlet.
- Run water without the disposal on and watch each connection point closely to find the exact leak location.
- If it's at the sink flange, the unit likely needs to come back down to redo the plumber's putty seal.
- If it's at the mounting ring, confirm the disposal is fully twisted and locked per the manufacturer's marks.
- If it's at the discharge tube, check that the gasket is present and seated evenly, then retighten the bolts.
- If it's at the dishwasher hose, check the clamp and that the hose is pushed fully onto the nipple.
Tools and parts
- Screwdriver
- Plumber's putty
- Towel
- Flashlight
Disposal discharge tube gasketSearch: “garbage disposal discharge tube gasket”
When to call a pro
If a fresh install still leaks after redoing the seals, or you're not comfortable pulling the unit back down, a plumber can correct the installation.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.