[keiuf61]

I'm getting a fowl odor coming from the bathroom sink.
The septic tank was pumped out three months ago.
There's no odor from any other drain in the house.

[beijer]

Check that there is water in the trap, that U shaped pipe under the sink drain. It may be leaking water and thus not sealing the drain from sewer gases. There should also be a clear vent of that part of the drain system that may be blocked.

[ballengerb1]

If your trap is working that odor probably isn't sewer gas but it could be roting hair and body oil. Try mixing 1/2 cup table salt with 1/2 cup baking soda and dump in the drain, now follow with a cup of vinegar. Tomoorw flush with a bucket of very hot water.