We just bought a brand new dishwasher from Ikea, called a Lagan. (https://www.ikea.com/ca/en/p/lagan-built-in-dishwasher-white-80462167/)

But it leaves behind a thin layer of dusty residue on everything.

We use a tablespoon of powered dish washing detergent in both wash compartments. And we use a rinse agent. Nothing really works.

Our water is from a well. We would call it mildly hard.

We have gone back to washing dishes by hand because this is ridiculous.

Does anybody have any suggestions? Thanks.

Edit: By "dusty" I mean "stuck on or baked on powdery substance, that does not feel soapy when wet, the same stuff that coats our pots after we boil water" Hmmm... Yes, this sounds like minerals in our water. Maybe we just need a water softener. Thanks, commenters.

  • 2
    Have you used a dishwasher with out problems in the past? I ask this as hard water can cause the the residue look even with a surfactant like jet dry. I would see if the rinse agent or jet dry is adjustable (some are) increasing the amount breaks the water tension and reduces the hard water residue.
    – Ed Beal
    Sep 6, 2021 at 17:13
  • 1
    Do you have similar problems in your kettle, tea pot, shower head, and so on? Is the "dusty residue" actually calcium or other mineral deposits, or is it actually dust, lint, or something like that? Can you blow it off the dry dishes? My guess is it's mineral deposits' and @EdBeal's comment is correct, I'm just a little hesitant because you call it "dusty".
    – jay613
    Sep 6, 2021 at 17:43
  • Please clarify "dusty": does it easily swipe away clear with a finger, does it feel greasy? Does it become soap-slippery when moistened? Is it a milky looking residue, does it feel etched in? This should help distinguish between alkalinity, mineral deposit, poor drainage... each having a different solution.
    – P2000
    Sep 6, 2021 at 17:56
  • What brand dish detergent are you using? I was ready to buy a new dishwasher before my brother told me he had the same problem and determined the detergent from Costco was crap. Try a name brand detergent and a good rinse agent. Have you had your water tested? A report of that would help us help you better. Sep 6, 2021 at 18:20
  • Please be sure to give Ed's answer a check-mark click so that others know this has been resolved!
    – FreeMan
    Sep 7, 2021 at 12:36

2 Answers 2


I believe the residue to be hard water residue, some brands of dishwashers have adjustable surfactant (the jet dry liquid) added to the final rinse.

I believe there are also dishwasher detergents formulated for hard water.

I have lived in a home with a water softener and you could really taste the difference when out of salt. I know the jet dry helps as we could see the difference when this ran out also.

I mention jet dry as that is the only brand I know of and many dishwashers I have had / installed usually mentioned this by name.

  • 1
    There are even dishwashers with built in water softeners. My well water is so hard that it requires a lot of treatment and, yes you can taste the difference if it runs out of salt. We installed an RO (reverse osmosis) filter for a couple of dedicated faucets and that helps a lot. Sep 6, 2021 at 21:08
  • Our dishwasher's manual said to use more detergent for harder water, so we tried adding as much detergent as physically fits in the two dispenser containers. This seems to work. I suspect better detergent would be even better, and a water softener would be even better. Thanks.
    – Magmatic
    Sep 8, 2021 at 0:15

Well, a few months later it appears we found something that works. Our dishes come out clean now. The answer was that we started using liquid detergent instead of powered detergent.

  • Normally I would recommend against liquid detergent, because you are (essentially) paying to have water mixed in. But if it works, that's what matters. I wonder if there is some other ingredient in this particular detergent that makes the difference, or if it is simply that it doesn't have to dissolve in the water because it comes already in solution. Nov 28, 2021 at 3:08

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