Sewage smell from dishwasher - help (pool, drain, sink, smells)

[motifone]

Hi All,

I'm having a problem with a foul rotten-egg smell when I start running our dishwasher, which I've heard can be coming from sewer gases. House is about 6 years old. Dishwasher drain line runs up to an air gap on the sink, and that water returns down into the garbage disposal, which then exits out into the main line.

The only time I smell this is when I first start to run the dishwasher. The smell lasts for a few minutes, and then dissipates, but it has grown stronger over the past year(which is why I am posting for help, hah!) I do not get this smell when running the garbage disposal or sink for other purposes. But the smell is now strong enough to fill the kitchen -- not just smelled when by the sink.

I've read this smell can sometimes be caused by the dishwater line being installed on the sewer side of the p-trap, but that doesn't seem to be the case here.

Any thoughts? An issue with the disposal? Things to check?

Thanks!

[K'ledgeBldr]

The drain/pump screen is probably partially clogged with the debris/food particles; this does two things- first the D/W doesn't completely drain, leaving water. Then there's the particles/food sitting and decaying.

Everytime you startup the D/W you stir it up creating the obnoxious odor- the reason it goes away after a few minutes is probably due to fresh water mixing and the detergent.

Some screens are relatively easy to clean, others are a process. If you have the owner's manual, check it. If not, a search of the web should result in directions for the procedure.

[BostonMike7]

Had the same issue with my dishwasher. It was the drain line. I had it in a loop like yours and it just reeked every time I fired up the dishwasher. Dirty water just sat in the loop and would reek when I turned on the dishwasher and it did it's initial drain line purge. Smell was bad enough I had to open windows.


I shortened the drain line and adjusted it more like this, and the problem went away....completely.

[sj08054]

Definitely shorten the clear drain line. You have an air gap installed. No need to have the excess and loop.

[motifone]

Thanks all. I'm going to try shortening the drain line. I'm pretty good on cleaning the drain pump screen regularly, so don't think it's that. Il'll try the drain line.

[Hedgehog_Mom]

I was going to say the same thing about the drain line. I didn't shorten mine, I just used a cable tie to attach it to the underside of the sink so water couldn't pool in it, and it's been good ever since.

You can also get those Lemi shine packets for the dishwasher and use one once in a while. They stink but the machine smells great afterwards and all the racks are super clean and shiny again.

[oregonwoodsmoke]

Have you cleaned the filter in the dishwasher?

You don't need to shorten your drain line, you need to raise a loop of it much higher than it is now.

[motifone]

An update: so rather than cutting and shortening the line, I followed the advice to try raising it up to get the loops out of it. I secured the drain line to the height of the sink, but even in doing that, there’s still some loops and/or flat points where water can settle. I’ve run the washer twice since doing this, and though there is less smell (and less water being purged when the dishwasher starts up) there is still some smell.

I think I need to somehow shorten the line by cutting it, but I’m not sure where to cut. Atatched is a pic of the drain line as it currently connects to main dishwasher line. I’m noticing the drain line is mostly ribbed, except the end where it connects to the main line (same on the opposite end). But to shorten the line, I’ll need to cut off a large chunk into the ribbed section. How will this line connect back in? Am I better off buying a shorter line?

[K'ledgeBldr]

Shorter line, or one of these puppies-

[TBayFlorida]

We had the same smell issue every time we turned our dishwasher on and it's embarrasing to admit we were dumbfounded for years without figuring out the cause. We raised the issue twice with two different plumbers (when having our broken disposal replaced on one occassion and again when having our worn out faucet replaced on another occassion) but neither plumber could find any problem to account for the smell each time we ran our dishwasher and once the diswasher had been running a few minutes, the smell would disappear anyway.

Eventually, when we had our old dishwasher replaced with a modern top of the line replacement, we assumed (or hoped) the issue with the disposal smell each time we had run the old dishwasher would be resolved too, but we were wrong.

Having run out of ideas as to the cause, we ran across helpful tips online which others had posted about the drain line between the diswasher and the disposal and sure enough, by simply reversing the loop in the drain line, we completely eliminated the odors ever since!

By reversing the loop, I mean the drain line had enough slack that it had been looping low below the height of the disposal connection, so basically we just lifted the loop up high under the sink and attached it up high so it would stay in place well above the disposal height with no place for water to settle in the drain line that might come from the disposal.

Imagine all of the times a disposal fills with water and food debris before being turned on or while being run, because any drain line connected to the disposal that loops downwards, is just acting as a resovoir collecting foul water and food debris from the disposal until the next time the dishwasher is run again which instantly pushes the debris back into the disposal along with the foul smells. It was a very simple fix as it turned out, but I remain baffled as to how some licensed plumbers can't recognize that problem!