Why the bottom leaks
A disposal has seals between the grinding chamber, where water and food go, and the motor below it. Over years of use those seals wear, and corrosion can eat through the chamber wall itself. Once water gets past them, it drips out of the bottom, sometimes from the reset button opening or the wiring cover plate.
Hard water is a factor in many North Orange County kitchens, including Fullerton's, where the city's supply blends local groundwater with imported water. Mineral content does not by itself cause a disposal to fail, but scale and corrosion together tend to show up in older units. Age is the biggest predictor: a bottom leak on a unit that has been in service for many years is a common end-of-life sign.
Make sure it really is the bottom
Dry the whole unit
With the power off, towel the disposal, the hoses and the cabinet floor dry.
Run water without the motor
Run a little water into the sink while the disposal stays off, and watch.
Trace drips upward
Water often runs down the outside of the housing from a higher leak. Follow the wet trail to the highest wet spot.
Note what you see
If the highest wet point is the bottom plate or reset opening, it is an internal leak. If it is higher, read the flange or side-connection guides.
Repair or replace?
Why repair rarely makes sense
- Internal seals are not usually sold as a simple part
- Corrosion often means the chamber is thin elsewhere
- Labor to open the unit approaches the cost of a new one
- The motor may already have been exposed to water
What replacement involves
- Removing the old unit and its mount
- Often a new flange and gasket at the sink
- Reconnecting the drain and dishwasher hose
- Testing for leaks and checking the drain downstream
A typical sequence once you notice the leak
- Right away
- Cut the power, stop using the unit, put a pan underneath.
- Same day
- Photograph the unit and its label, and note the space under the sink.
- Before the visit
- Decide whether you want to supply a unit or have the plumber bring one.
- At the visit
- Old unit out, new unit mounted, drains reconnected and tested.
- Afterward
- Check the cabinet floor for water damage once it has dried.
What drives the cost
The new disposal itself, the motor size and features you choose, whether the sink flange is replaced, how easy the cabinet is to work in, and whether the drain or dishwasher hose need new parts all change the total. Ask for a written price that lists the unit, parts and labor separately, and whether haul-away of the old disposal is included.
Questions to ask
- Are you sure the leak is internal and not from a connection above it?
- Does the price include a new flange and gasket?
- Will you check the trap and drain line while the unit is off?
- What is your CSLB license number?
Common questions
Can I keep using a disposal that leaks from the bottom?
It is best not to. Water near the motor and wiring is a safety risk, and the leak will usually get worse.
Could the leak be from the reset button only?
Water at the reset button almost always comes from inside the unit, which points to failed internal seals.
Will a new unit fit the same mount?
Sometimes, if it is the same mounting style, but many installs use the new unit's own mount. Ask the plumber which applies.
General information for Fullerton, not a quote or professional advice. In an emergency, call 911.