Smell coming through P-trap

[BDelph]

I have a pedestal sink in an upstairs bathroom. It has a plastic P-trap going into a vertical vent pipe in the wall.

Everything works fine except when I first start running the water, a sewer smell comes up for just few seconds and then dissipates. Its almost like the trap "burps" and lets some bad air through and then it refills and works as designed.

Any thoughts on what this might be?

Thanks.

Bill

 

[majakdragon]

As long as the trap is full of water, there should be a seal in it that prevents odors of sewer gas. I am guessing that the smell is from the sink itself. If the sink has an overflow hole, bacteria can grow between the double walls of the sink. When you turn on the water, the pressure pushes foul air out through the overflow. Try using the stopper on the sink and close it. Pour in one cup of household bleach. Slowly run water into the sink (so the bleach does not splash). Let the water run until the bleach smell is gone. This should fix the problem. Good luck.

 

[mike1234]

May be there might be a blockage somewhere which does not allow the water to pass easily.

 

[BDelph]

It seems to flow just fine.

The smell is very regular and predictable. You start the water, and a minute or so later, you get a funky sewer smell. It lasts for a few seconds and then its OK.

The time it takes to smell it is about the time it would take to empty and then fill the trap from the faucet.

Very curious. My mother-in-law thinks my plumbing is the cause.

:-{

Thanks.

 

[Caduceus]

Did you flush the overflow as majakdragon recommended?

 

[SlowDrip]

I suppose there could be an air bubble in your trap which is being released when more water is added. I'm not sure how such a bubble could be recreated frequently, however.


It is also possible that the smell is actually coming from gunk in your copper lines. Try putting a stopper in the sink and running the water water to see if you still get the smell.