Before I started barking up the wrong tree, I wanted to run this by the pro's.

I noticed a slight odor from my kitchen sink drain. It might occur during dishwashing cycles. When the dishwasher is done we don't notice it when using the sink as normal. There are no other drains being used in the house when this occurs.

There is also no blockage, the sink drains as I would assume it should. When the dishwasher is running, I can feel warm/hot water sitting in the trap so I am not sure if its siphoning is occurring.

Dishwasher drain is looped high and then drains into the tailpiece above the trap.

The sink is not connected to the main vent, rather a 1.5" smaller galvanized stack.

Does this sound like a restricted vent?
Is it possible for the dishwasher to siphon the trap it drains into? (my thinking is "no", that if its vent was blocked, it would siphon another trap elsewhere to achieve the air needed to drain?)

IF it were a blocked vent, and the possibility is VERY remote, it would happen when you used the sink also, and that would be more frequently tnan the dishwasher. Someone would have to be there and make some tests to see if the source could be found. Odors are very difficult to trace, because they can occur in one place but be smelled elsewhere, usually in a "pocket" where they can accumulate.

is my reasoning correct that if it was a blocked vent, the dishwasher would siphon the trap it drains into but rather another trap connected to that same vent?

also..its not hard to track to the sink, as I put my nose directly into the strainer area and I can smell it. I don't have a disposal either.

Thank you for your time.



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WHENh you smell it look down the drain with a flashlight to see if there is water in the trap, if there is there is no siphonage, and the dishwasher would ONLY siphon that trap if it were a vent problem, or one NEXT to it, if you have a bad installation.

Just to claify since I wrote it wrong...

If the vent was restricted, then the dishwasher WOULD NOT siphon the trap its draining into... instead it would siphon another trap next to it connected to the same vent.

When the dishwasher is draining, and when I detect the slight odor in the sink, I do see water in the trap I think... its a baffled fitting but I see water moving around down there.

Also- Is the fact the sink draining quickly from full with no sucking air sounds any indication that its not the vent?



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might be all that nasty bio accumulation that tends to build up on the inner walls of drains under the kitchen sink. replace the tail pieces, traps, cont. waste with new and repost here with your good news?? also a good time to remove all the contents under the sink and disinfect cabinets walls and base too.



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I replaced all the plastic under the sink a few months ago.

For problematic smelly drains try a bacterial drain maintenance product such as Bio Clean. The organic matter in the drain is what causes the odor as it decays and a bacterial product like the one I mentioned will eat that matter thus eliminating the odor. Works like a champ! I am not promoting Bio Clean but it is the only product I know of for this use. I use it in my shower drain when it gets to stinking and within 24 hrs the smell is gone.

What other trap could be connected to that same "vent", especially since you DO smell the odor in the sink? IF it is a baffled tee, then both sinks and the DW drain into the same trap.

are you sure you "replaced" them EXACTLY the way they were, or did you "revise" them to make them better?

Theres no other traps connected to that vent.

Is it safe to assume that no sewer gas is escaping thru the trap if indeed I see water in the bottom of the trap from above?

Then I might rule out the vent and look to the dishwasher itself.

If it was a venting issue, wouldn't I see a slow drain as well?


also - I see the water in the bottom of the trap moving slightly when toilets are flushed and sometimes when nothing is being used. Not sure if that's normal atmospheric movement of some sort.



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It could be an installaton problem, but probably not related to this problem.

i could be the plastic/rubber drain hose from the dishwasher. i might have an accumulation of smelly gunk that you only smell when it discharges ??
only a guess..

Is it abnormal to see the water in the bottom of a trap moving?

kind of like you see on a windy day with some toilets.

No other fixtures in the house are being used and I still see some movement in the trap.

And what about the fact that its not a sluggish drain?



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Wind currenat flowing past the top of the vent will create pressure changes inside the pipe and make the water "jiggle", but that also means the vent is working properly.