I have an In-sink-erator model garbage disposal with a black plastic housing. After fixing a jam (a shot glass that fell into it while running, quite destroying itself), I noticed that there was water appearing under the sink. I traced it back to the side of the unit where a small ~3 mm/0.125 in hole has appeared. Additionally, there is some white crud building up around the attachment ring and around this hole. The plastic itself appears to be corroded, as it has a rough texture near where the white crud is.

Corroded insinkerator showing a leak hole center and patches of white build up on roughened black plastic.

When a large enough volume of water goes down the drain or the disposal is run with water in it, water comes out of this hole at rapid pace.

I'm set on replacing the unit, but I'd like to know what caused the corrosion to hopefully prevent it in the future. We keep a number of cleaning supplies under the sink – vinegar, liquid bleach, carpet cleaner and deoderizer, powder dishwasher detergent. I thought the powdered cleaners such as Comet and AJAX were what you had to keep away from plastic plumbing, is that accurate?

  • is that hole in line with the impeller? if it is, then that is a "bullet hole"
    – jsotola
    Dec 30, 2017 at 23:26
  • I had leaking under a sink a few months ago - holes & corrosion in the Insinkerator. The unit was > 20 years old (another one ~ 17 years old is still going strong). If it is > 10 years old then I'd guess you probably got a reasonable life out of it and just go ahead and replace it. I got a replacement (same basic model as before) for around $100 and it took < 1 hour to replace it - one of the easiest fix-it jobs I've had in a while. The new unit even included very clear replacement instructions - I thought I'd have to rely on YouTube. Dec 31, 2017 at 2:36

2 Answers 2


a shot glass that fell into it while running

It's pretty obvious the glass shattered and chunks were flung against the wall. Note how there's a line where the hole is. Since the bottom of shot glasses is thicker than a normal glass, it probably got enough velocity to puncture the wall (and you're lucky that's all it did)

I'd like to know what happened here to hopefully prevent it in the future

Don't put shot glasses down the disposal. ;)

  • I'm mainly interested in preventing corrosion to the replacement unit. The shot glass I know not to do and how to prevent it :)
    – Patrick M
    Jan 5, 2018 at 21:02
  • The unit itself is going to unavoidably corrode in some fashion. They only last 5-10 years in my experience. Eventually the seals break down and you have to replace it.
    – Machavity
    Jan 5, 2018 at 21:05

Looking at the image it appears that the housing is some type of cast metal. The white residue is typical of corroded aluminum. My guess looking at the line of white spots is that"s where the glass hit the inside of the housing. It may be that the corrosion has been going on long term and the glass was the final straw. Not all dishwasher detergents are friendly to aluminum. If this is true of your detergent, it may have accelerated the corrosion.

  • +1 It might look like plastic but it is not. The grind chamber is metal and susceptible to corrosion, especially if caustic/corrosive cleaners are flushed into/through it. I agree that the glass shrapnel was probably the final straw for this unit. Some models have stainless steel grind chambers that are less susceptible, but they cost more $$. Dec 31, 2017 at 1:03

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