I've read through several of the posts on this site and have done numerous searches across the Internet. So far, no luck... About a week ago we noticed a strong sewage smell coming from the toilet in our powder room. After cleaning the bowl with bleach (thinking it was bacteria), the smell was still there. Yesterday we completely uninstalled the toilet, replaced the wax seal (which seemed to be in okay shape), and reinstalled. We also placed a bead of caulk around the bottom of the toilet, hoping to prevent any further smells from seeping out. To no avail. Today we climbed up onto the roof to check the vent pipe, and snaked it to about 15 feet -- it came out clean, but we can't be sure the snake is long enough to know if there is definitely no blockage in the pipe. We assume the vent is shared between the toilet and the sink, but no odors come out of the sink, so are guessing that's not the culprit anyway. Tonight we'll try pouring bleach into the tank, scrubbing walls and fixtures, and then flushing it through tomorrow (as suggested in a separate post). Any other ideas what could be causing this? The water level isn't too low, nor do any of the other usual suspects seem to be the cause. Help?

I have the same problem. I was thinking of pulling up the toilet. Since you tried that and it made no difference, I won't bother. Did you notice if the smell was indeed in the drain under your toilet? Was there any visible "liquid" backed up in the drain? Was there any build up in there or in the underside of the toilet? DId anybody answer your last post?

If you are not sure if the snake is long enough, get one that is. It definitely sounds as though it is sewage gas coming back to the inside. Is the vent pipe up through the roof of your house, or is it on the outside wall of the house? Have you checked underneath the house to be sure you have no leaks? Are you on a septic tank system, or public sewer? Also, if you have a "grey water" drain, this is water from anything besides the toilet(s), this water can believe it or not have a more offensive odor than sewage from the toilets.