Mold in dishwasher

hhirenoNovember 15, 2010

My 1996 Kitcheaid Superba dishwasher has developed a mold problem. I've scrubbed it out, checked the water temp at various parts of the cycle, and ran a cycle using Tang but the mold is returning.

The dw was re-installed, after a renovation, in 2001. The mold started early fall 2009. Most of the year, we run it about every other day. Certain times we use it once or twice a day.

When I bought the KA I picked it only because it was replacing a 23 yo KA so I figured I'd stick with that brand. No research. No agonizing. Just "I'll take that one."

Now I have been researching dw until my head spins and I end up locked in confused indecision. And that was before I even knew about I had to worry about water softness, phosphates in soap, rinse aids, and all the things I read here.

Either my expectations are low or I was very lucky with the KA up until the mold started.

I also have to replace my Jenn Air range with another since I can't reconfigure my kitchen and that expense (approx $2500) is negatively influencing my thoughts on how much to spend on a dw. The only positive there is maybe buying 2 appliances will help my bargaining position.

Since there is such great advice here I want to ask:

what can I do to make sure the mold problem doesn't happen in the new dw? Is it wrong to hold a grudge against KA?

Thanks for any advice you can offer,



Thank you for reporting this comment. Undo

Are you using heated cycles to get the water temp up where it might dry out between cycles? Did it ever NOT have a mold smell problem? Are you using a drain air gap to prevent back syphoning? These questions lead to the cause of your problem. As to a possible cure, I suggest adding just a half cup of Chlorox to the bottom of the tub and do a hot wash. Then do a repeat with only a couple of tablespoons. That should kill the mold spores and if you use heat to dry it out between washes I hope that would prevent the return of mold. Did you change from having an air gap to not having one during your remodel?
Sorry to hear of your problem.

    Bookmark   November 15, 2010 at 1:34PM
Thank you for reporting this comment. Undo

Can you say what the temperatures you measured were? Can you say locations within DW where mold observed?

I'm suspecting temperature issues or drainage issues.

    Bookmark   November 15, 2010 at 2:29PM
Thank you for reporting this comment. Undo

Thank you so much for your prompt replies. FYI the model number is KUDS23HB.

Let's see if I can provide answers to your questions:
The mold just started, to be noticable anyway, late 2009 and it had been re-installed in late 2001. There is not/never was an odor, just black gunk.

It started after a period (in August-Sept when it is hot & humid here)when the dw was rarely used for a few weeks & I think dirty dishes were left in it. At first, it was just the utensil basket but evetually spread to other areas. If it is mold, perhaps it was there but not visible, besides the utensil basket, until months later?

I only ever use Normal cycle/energy saver dry. I have generally used Cascade Complete gel as detergent. I might have used Cascade powder prior to the re-install but I don't remember. I will admit I never looked at the manual until a few months ago when the mold started. I never knew, until reading here, that I should be thinking about softness of water, phosphates, type of detergent etc. Ignorance was bliss.

I don't know what a drain air gap is.

I can't remember if it was reinstalled by the plumber or the contractor. If it was reinstalled incorrectly, could it take this long (8 years) for a problem to develop?

The black gunk (which I assume is mold) is on the gasket at the bottom of the door, the inside bottom edge of the door, streaking down the door, the utensil basket, where the soap dispenser attaches to the door, streaking on the floor near the lower spray arms, a little bit in the crevices of the metal spray arms, and the most visible on the upper arm spray inlet.

I soaked the utensil basket in a sink full of bleach & water and scrubbed it with a clean toothbrush. It didnot remove the black but I don't think it has increased there. It has definitely returned to the upper spray inlet and the door area.

I tested the water weeks ago and this is what I remember. This dw fills with water and then heats it. I checked about mid-way thru the heating (120 F), right before the cycle started (130 F),and during a later, maybe final, rinse (160 F).

Even if it's a drainage issue that can be corrected, wouldn't I still need to get rid of the dw because of the re-growth/return of the black gunk? I did clean it before and the black gunk returned so I resigned myself to needing to buy a new dw.

For replacement, do I need to worry about mold existing in lines or pipes that would re-"infect" the new dw?

Accept for this problem, and it's a big & gross one, I haven't had any problems with the dw. I've never had a service call. If I could keep it safely for a few more years it would be a bonus to offset the cost of stupid Jenn-Air that I have to replace.

    Bookmark   November 15, 2010 at 3:14PM
Thank you for reporting this comment. Undo

Temps sound right. Now I would focus on drainage issue. Mold needs something to grow on. Usual culprit in DW's is un-flushed food residue. Usual causes are obstructed drain hose or obstructed filter or masticator retaining food residue or not allowing all of it to pass out. The 8-year delay makes me think this may be correct. Such obstructions usually take time to develop. Often this is visible in retained water in the bottom of DW...but not always. Are you seeing particles on your clean dishes after a cycle, now?

These are simple things to check. I would start there. If that's it, a clean-up to remove/kill mold that's already there and a couple of hottest wash/rinse cycles should have you right again. Usual place for gunk to accumulate in drain hose is right where it connects to disposal or drain outlet. If disposal, also check the tube leading into the disposal itself. This is a favorite place for plaque to accumulate and obstruct.

From what you've said, I suspect this is not going to be a huge deal. I suspect your machine is fine but has been compromised by something simple. If you're not comfortable with handling this, by all means schedule a service call. I doubt it will be a long visit.

    Bookmark   November 15, 2010 at 3:29PM
Thank you for reporting this comment. Undo

Said that wrong....may have left the impression that just running the machine hot a couple of times will clear obstructions....which is NOT the case. If there are obstructions, they will need to be found and removed manually. After that, the clean-up and couple of hot cycles should have you right.

    Bookmark   November 15, 2010 at 3:38PM
Thank you for reporting this comment. Undo

Excellent! Thank you for the info & ideas on what to do. You may have just saved my $1000+.

Now that I have the actual "Use & Care Guide" out maybe I'll read it and use the machine correctly for the rest of its (fingers crossed) long life.


    Bookmark   November 15, 2010 at 4:17PM
Thank you for reporting this comment. Undo

one more thing to check for - since it sounds like you don't have an air gap - you would see it on your counter if you had one - then you need to have a high loop in the drain hose from the DW before it connects to your disposal or sink drain. If you don't have one, then dirty water can back up into the dishwasher.

    Bookmark   November 15, 2010 at 4:30PM
Thank you for reporting this comment. Undo

You might want to NOT use the engery saver dry and let the heated dry run. At least once it a while. Mold needs moisture. If you use it and there's still moisture in there, you likely have some drainage problem.

    Bookmark   November 15, 2010 at 4:51PM
Thank you for reporting this comment. Undo

Air gap: that thing on the back corner of the sink, about 2" high with a chrome cap, that appears to be useless. It is that thing that the dw is attached to, and from there it drains into the disposal (if you have one) or the sink drain.

Energy Saver Dry: You are giving the mold a nice, warm, dark place to breed and multiply. Stop using it. At least for a while. And leave the door cracked open between uses so it can air out.

I'm guessing the liner of this unit is plastic, not stainless?

You should, if you haven't already, wipe down the gasket with a bleach solution, plus the other surfaces. You should probably do this as a preventative once a week until the problem goes away.

    Bookmark   November 15, 2010 at 5:15PM
Thank you for reporting this comment. Undo

Thank you all for your replies. I've made note of all the comments and suggestions so that I can get this solved. This place is the best! Jean

    Bookmark   November 16, 2010 at 11:37AM
Thank you for reporting this comment. Undo

Also, you should go to the trouble of removing the entire drain line from the dishwasher to the garbage disposer or drain to check the hoses for obstructions. I have gotten little pieces of bone stuck in my air gap before. it made the washer have smelly water in the bottom at the end of the cycle. You could have just enough of something to prevent normal draining. This can be wet and messy so I would kick in for a repair. I am beginning to wonder if the black deposit is really mold. Could something be coming off the surface and exposing a black plastic that is normally under the finish?

    Bookmark   November 17, 2010 at 2:36AM
Thank you for reporting this comment. Undo

The above is great advice. I would however also recommend that you get a proper mould-killer or fungicide. Bleach is often ineffective at killing mould and, if you don't kill all the spores, it will just keep returning and spreading. And when you do apply the fungicide, you need to get into all the door seals, etc. as these are common places for it to "hide". It can be a real PITA to do a thorough mould clean up but it might be worth your while.

    Bookmark   November 17, 2010 at 6:37AM
Thank you for reporting this comment. Undo

Hello again,
I'm back with an update & a question for the kind experts in this forum.

The above mentioned KA started to make some odd noises, clicking and what have you, so I decided I should start thinking about a replacement before it was an emergency situation.

A local appliance place was offering free delivery, free installation, and haul away. Turns out they had recently rcvd an email from the Miele rep that there were 10 white dw marked down for clearance. As luck would have it, I am one of the few people in the world who wanted a white dw.

I was able to get a Miele G2142 delivered, installed by their qualified installer (extending my warranty by a year as you know), & the old one hauled away for $899 prior to the tax. Please do not burst my bubble that the deal wasn't as good as I convinced my DH it was.

Even though it's an entry level Miele, I'm excited to be joining the ranks of fancy German dw owners. Next, maybe I can talk my DH into a fancy German car.

Anyhow, it was installed yesterday and I have yet to run it. They did run an empty cycle to check it out - oh my! how quiet compared to the older one they removed.

Based on reading old posts, is the following a good plan? I will use no more than 1 Tb of Cascade complete for a full load and can use either Jet Dry OR plain vinegar as the rinse aid. Does that sound okay?

I don't know if it matters but I did check with our water supplier and the hardness is 1 grain.

Thanks in advance for your suggestions.

    Bookmark   March 26, 2011 at 4:17PM
Thank you for reporting this comment. Undo

Jean, that's a great deal and congrats on your shiny new white DW!

    Bookmark   March 26, 2011 at 7:58PM
Sign Up to comment
More Discussions
Any thoughts about Bosch and GE Profile appliances?
I am building a passive house and trying to choose...
Wolf is increasing the BTUs on front burners
When I called the Wolf showroom in Atlanta, I was told...
I am about to purchase a dual –fuel, 30 “freestanding...
24' Appliances: Liebherr or Fagor?? Bertazzoni or other?
Can anyone weigh in on small space appliances? While...
1200cfm oversized hood...Overkill for 30" BlueStar range?
I am getting a 30" BlueStar RNB range for my kitchen...
Sponsored Products
Cocktail Tray
$38.00 | FRONTGATE
Chelsea Martini Glass (Set of 4)
Color Pop Tumblers - ORANGE
$45.00 | Horchow
Sofia the First Place Mat
$4.49 | zulily
Lenox Colonial Tradewind Saucer - Set of 2 - LNOX1646
$33.90 | Hayneedle
Zephyr 30W in. Gust Under Cabinet Range Hood - AK7100AS
$499.00 | Hayneedle
Pasta Tongs
$10.99 | zulily
Berry & Thread Chip 'N Dip - WHITEWASH
$98.00 | Horchow
© 2015 Houzz Inc. Houzz® The new way to design your home™