I am hoping someone can help me! This all started with an odor in a room that shares a wall with the bathroom. The bathroom, however, does not have an odor. The sewer vent goes through the wall in between, but I have cut into the drywall where the pipe enters the room and there is no smell. It could run under the floorboard, but I'm not sure. I have noticed now that the water level in the toilet slowly sinks throughout the day. There is no gurgle and it seems to flush normally. I have already had a plumber to the house, and he could not find anything wrong. I am thinking of pulling up a floorboard to see if there is a small leak under the floor. I have already pulled up the rug to see if it was mold... it was not. I am stumped and frusterated. PLEASE HELP!

There are a few things that could take your level down. There could be a crack in the bowl letting the water seep out over twenty minutes. That would be my first guess. My second guess is kind of far out but since I've had a couple of calls that lost water in the bowls, I'll throw it up for grabs. The water in your bowl is a trap/seal and connects directly to a pipe called a vent located on your roof. If that location is windy, it has been noted that the wind blowing over the vent pipe causes a suction that syphons the water out the bowl. But that's rare and you will notice the level raising and falling as it happens. I'm going to go with door #1 if only because of the time it takes for the level to go down. The only fix I know is to change out the bowl. The only bright spot is that it's possible that you won't need to buy a whole toilet assembly, a large plumbing shop should have bowls that will match your old tank. If you decide to do the work yourself, click on back and I'll walk you through the installation, Good luck, TOM

Is this something on the first or second floor? Im not sure how you could be losing water through the bowl other then a leak in the toilet itself. The curve that it makes acts as a seal and that water level should remain steady other then evaporation. Also are there any sinks or outlets your not using? If they dry out you can get a smell and it may have migrated.

Thanks for your response. It is on the second floor, and it takes several hours for the water level to drop really low. Currently, there is no water damage visible. The smell is only in the room behind the toilet. Could a break/leak in a vent vipe cause water in the toilet to recede over time?

No, a leak in the pipe won't do that. You might want to read speedball's answer again.

Would a crack in the bowl then leak into the floor ad cause the smell? Wouldn't I see water damage? I think the sinking toilet bowl water and smell are connected...

would a crack in the bowl then leak into the floor ad cause the smell? wouldn't I see water damage? I think the sinking toilet bowl water and smell are connected.......

If it is leaking to the interior and outside the seal it could be leaking past that section and following the pipe. Its hard to speculate without being able to see. You state no stains in ceiling so its really hard to say where its going. You might have to replace the gasket and pull up the floorboard and take a look the hard way.

would a crack in the bowl then leak into the floor ad cause the smell? Wouldn't I see water damage?
Not necessaraly. If your bowl, Had a hidden crack or a manufactures defect the water would seep into the closet bend and out into the drain line.
I've been faced with this problem before and about the only way to check it would be to pull the toilet, set it up on saw horses and fill the bowl. Set a paper under the saw horses and leave it for awhile. If there's water on the paper when you check back you have a faulty bowl that must be replaced. Good luck, Tom