Our bathroom has a foul odor coming from it. We have done all the required troubleshooting that we know of. We have no clog or hair in drain but asmell is coming from under the sink. It's almost like it is in the cabinet below the sink. We are on a slab and have pulled the shelf up and nothing is under it but cob webs. Any idea where we go from here? Thank you. Babywhoban

Flush the toilet. Sorry had to say it. :D

When you say "under the shelf" you mean under the vanity unit itself?

Yes, under the shelf which when pulled up is the floor and under that is the slab our house sits on. Strange. Would the smell be coming from the pipes? We have well water and we were wondering if after a length of time the pipes would be corroded with rust and whatever. This just started smelling one day and it has smelled that way since. Which is too long!! Thanks. Babywhoban

Have you pulled the plunger and looked down the drain? There's a little rod down there that hair hangs up on and starts to rot. May I suggest the next time you have a plumbing question that you post it on the plumbing page. It will get answered a lot sooner. Regards, Tom

We have already tried that. Babywhoban

Then this is one of those problems where you just have to be there to track it down. Have you considered a critter might have died inside a wall?
Good luck, Tom

There is no way for anything to get under our home. It is definitely somewhere under the sink in the vanity. Could well water cause this smell? We appreciate all your help. Babywhoban.

Do you have a "p" trap on your drain? If you don't and there is just a straight pipe running to your sewer you could be smelling gasses coming up from your sewer.