# Kitchen Island sink odor



## SixStrRzr (Jan 25, 2010)

I have a foul odor that appears to be coming from my island sink area in the kitchen. The island has a dishwasher and a large, single sink with a disposer. The island also has a small vent with a metal top in the countertop near the faucet. The odor only appears in the kitchen, all other sinks are odorless.

The sink drains free, as does the dishwasher. 

How does this small surface vent work? Could it be plugged up? Should I run some baking soda and vinegar down the sink? Should I pull & clean the sink trap?


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## TheEplumber (Jul 20, 2010)

The air gap (or vent as you're calling it) on the counter top is for the dishwasher. Should be nothing wrong with it. How is the sink vented inside the island? Is there a loop vent or a auto air vent? If there is an AAV, It may have failed and is allowing sewer gas into the cabinet.


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## SixStrRzr (Jan 25, 2010)

TheEplumber said:


> The air gap (or vent as you're calling it) on the counter top is for the dishwasher. Should be nothing wrong with it. How is the sink vented inside the island? Is there a loop vent or a auto air vent? If there is an AAV, It may have failed and is allowing sewer gas into the cabinet.


It must be an AAV,as there's no top vent to the roof. Where is the AAV located?


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## Jackofall1 (Dec 5, 2010)

An AAV should be accessable, so I would think it would be under the counter near the sink.

Mark


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## SixStrRzr (Jan 25, 2010)

Where are AAV's available? I checked the Big Box stores, none have them. Maybe a specialty plumbing store?


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## Homerepairguy (Aug 1, 2010)

TheEplumber said:


> How is the sink vented inside the island? Is there a loop vent or a auto air vent? If there is an AAV, It may have failed and is allowing sewer gas into the cabinet.


How does an AAV actually work to allow air into the drain but not air out from the drain? Just trying to understand the concept.

Thanks,
HRG


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## VIPlumber (Aug 2, 2010)

HRG,

Here's a link to a video, http://www.youtube.com/watch?v=o44-NqTtYpc. Good stuff starts at about 1:30 mark.


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## Homerepairguy (Aug 1, 2010)

VIPlumber said:


> HRG,
> Here's a link to a video, http://www.youtube.com/watch?v=o44-NqTtYpc. Good stuff starts at about 1:30 mark.


Thanks for that link. Understand how it works now. :thumbsup:

HRG


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## andrugargy (Feb 9, 2011)

My kitchen sink is in the middle of an island. There is a vent pipe under the sink between the trap and cabinet.It up again but not back in the sink or drain, but since it happened, we had an odor for sink.We have not done anything else to sink or plumbing.
___________________
Kitchen Renovation


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## SixStrRzr (Jan 25, 2010)

Jackofall1 said:


> An AAV should be accessable, so I would think it would be under the counter near the sink.
> 
> Mark


I took a cursory look under my sink, and there's no AAV that I can see. Disposal, u-trap, no vent to roof (it's a sink island), slab foundation, 10-y/o house. 

Is there a possibility that the AAV (or somethink that acts like an AAV) is located in the dishwasher vent, located next to the faucets? The dishwasher vent has a metal pop-off cover, and also has a plastic piece in the top that pops out, but I'm not sure what this piece does.

We've been in this house for 1 1/2 years, and the odor has only been prevalent in the last month or so.


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## Homerepairguy (Aug 1, 2010)

SixStrRzr said:


> I took a cursory look under my sink, and there's no AAV that I can see. Disposal, u-trap, no vent to roof (it's a sink island), slab foundation, 10-y/o house.
> 
> Is there a possibility that the AAV (or somethink that acts like an AAV) is located in the dishwasher vent, located next to the faucets? The dishwasher vent has a metal pop-off cover, and also has a plastic piece in the top that pops out, but I'm not sure what this piece does.
> 
> We've been in this house for 1 1/2 years, and the odor has only been prevalent in the last month or so.


The dishwasher vent (air gap) next to the faucets should come "before" the disposal and P trap and prevents water from the disposal from being siphoned back toward your dishwasher. An AAV (or vent to the roof which you don't have) comes "after" the P trap and prevents siphoning the water out of the P trap along with better drain flow.

If all you have is the dishwasher vent and it is hooked up "before" your disposal/P-trap with no AAV, then I wonder if the water in your P trap is being siphoned out, allowing sewer gas to emanate from your drains and dishwasher vent? Verify that the water in the P trap is always high enough to seal any back feed of air from the sewer.

If your P trap is "always" filled with enough water, then the odor must be coming from the tubing that connects your dishwasher to your garbage disposal or from the garbage disposal itself.

$.02,
HRG


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## SixStrRzr (Jan 25, 2010)

I'l have to look closer at the routing - How would water be siphoned out of the P-trap? Negative pressue on the outflow side of the P-trap?

How could that be possible?

I'll look when I get home.



Homerepairguy said:


> The dishwasher vent (air gap) next to the faucets should come "before" the disposal and P trap and prevents water from the disposal from being siphoned back toward your dishwasher. An AAV (or vent to the roof which you don't have) comes "after" the P trap and prevents siphoning the water out of the P trap along with better drain flow.
> 
> If all you have is the dishwasher vent and it is hooked up "before" your disposal/P-trap with no AAV, then I wonder if the water in your P trap is being siphoned out, allowing sewer gas to emanate from your drains and dishwasher vent? Verify that the water in the P trap is always high enough to seal any back feed of air from the sewer.
> 
> ...


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## Homerepairguy (Aug 1, 2010)

SixStrRzr said:


> How would water be siphoned out of the P-trap? Negative pressue on the outflow side of the P-trap?
> How could that be possible?


With no allowance for air inlet venting "after" the P trap within a distance required by code, the P trap becomes part of the siphon path. See "Venting and auxilary devices" in this link for a wikipedia explanation:

http://en.wikipedia.org/wiki/Trap_(plumbing)

HRG


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