Recently, my dishwasher (Whirlpool ADG 9999M, about 10--15yo) stopped working with some standard error. After getting the manuals, I decided to inspect the drip tray: it was full of water. I removed/wiped most of the water and the dishwasher started working again. Now the tray is completely dry, but there's a lot of calcification build-up (see photos below).

Should I remove the build-up? And if so, how? Can I for instance use vinegar, or will it damage something? I can't really access most of the tray surface since there's a lot of stuff placed over it.

The reason why I think this can be related is that it has been suggested the drain pump may be blocked; the website says "remove and clean the pump", however, the pump does not seem to really snap off and I don't want to break something.

Photos: (1) the tray; (2) the build-up when I scratched it off and one place.

calcification on drip tray

calcification (scratched off)

  • (Is there really no tag for calcification? Maybe something exists and I don't know what it is, suggestions are welcome. Thanks.)
    – yo'
    Commented Jan 10, 2016 at 20:52
  • Are you sure that is calcification, and not dried up dishwashing detergent? Commented Jan 11, 2016 at 4:02
  • @JimmyFix-it It seems to react to vinegar the expected way, if that means something...
    – yo'
    Commented Jan 11, 2016 at 5:32
  • Do you have a water softener? Best way to prevent lime build up is to remove it before it gets into the system. 😊
    – ArchonOSX
    Commented Feb 10, 2017 at 22:30

1 Answer 1


Monthly vinegar use: a full cup in an empty washer on "pot-and-pans" mode with no heated dry.

This has kept my unit functioning well and lime/scale free since I tore it apart and discovered the pump, the "macerator", pretty much the whole lower works, plugged up with lime, scale, and a whole lot of solidified dishwashing soap. I predict that you will be disassembling the lower works, internet searches helped me tear mine down (along with trial and error and persistence) and put it back together.

I will never use bargain liquid or any type of granular soap again. I only use the gel pouches and it's been smooth sailing ever since.

  • Are you sure that this will clean calcification from an area where only very little of the liquid you put in the dishwasher is supposed to get? ...
    – yo'
    Commented Jan 11, 2016 at 5:30
  • No, it won't clean it from there, actually. Your question implies that the root cause of the liquid being where it wasn't "supposed to get" might be calcification in the pump, and after cleaning the pump (as you also propose in your question) this will help prevent it from reoccurring. Commented Jan 12, 2016 at 5:49

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