We have one bathroom in our house used by 4 people. Every once in a while, there is a strong sewage smell. It is intermittent, there is no certain time that it is present. I cannot pinpoint it to a certain drain or area in the bathroom. When the heat comes on, it is VERY strong when it is present (the furnace is next to the bathroom). I figured I would check here before I tried anything. Any help would be VERY appreciated.

It's impossible to track a smell if you're not there to sniff it down. Drains, toilets, and open vents cause most bad odors but we can't help much. We can only point you towards the most likely spot. Good luck, Tom

I tracked it down to the tub. I poured a half gallon of bleach down the drain, let it sit over night and in the morning ran boiling water down the drain. So far I have not smelled anything. If this does not work, any other ideas?

If the bleach doesn't work then you have rotting hair mixed with grease and the drain line should be snaked out and cleared. Ifyou need instructions on how to snake a tub click on back. TIP: You can't snake through the drain, you must snake from the tub waste and overflow. Regards, Tom