Rental-related, if not mine. One of my kids is in a college town townhouse rental.There has been a persistent odor of either sewage or dead critter, in the half bath only, for about 8 days. (We live 5 hours away, so can't help narrow down the odor.)

They say that they have sniffed with walls, vents, sink drain, and cannot find a smellier-than-others spot. "It seems to be the air." No other place in the townhouse has the odor. Their less-than-responsive landlord refuses to investigate.

The ground level is a garage, then there are two levels above that. The powder room is above the garage, and the pipes come in through the floor. While part of the garage has a drop ceiling, the part under the powder room does not. The kids have also checked in the area under the powder room, and in the drop ceiling area - for odor/dead critters.

We've come up with two possibilities - dead critter in the wall, which the odor of which should fade soon. Or - blocked plumbing vent stack, which might be sucking the trap dry when the toilet is flushed or other plumbing used.

We are not, alas, on the lease, so we can't pester the LL ourselves, we just want to help the kids figure this out.

What Ken said. Probably a washer drain or some other dry p-trap.

You said it was "just the air". Just maybe....also check where the air gets drawn into the gas furnace too. See if there's something dead nearby (or in it), either at the outside connection, or right by where the connection meets the furnace.

We have this same issue at times in one of our rentals. We had someone come out and check the vent stack and it was clear. It only happens on occasion (according to the tenants) and we are never there when it does.

The toilet, sink and tub are used daily. Laundry is on the other side of the house and used frequently.

Vee, can you expound a little on your proposal above? Why the hot cocoa? And do you mean that the paper will actually move, or that the cocoa liquid will be drawn into the cracked wax ring? Are the strips placed tightly against the base?

We're doing this long distance, so I want to be able to communicate clearly with my kid.

The landlord came over, listened to what the kids had done, did the same himself, and said that he figured that it would go away. He apparently has a cash cow of a row of townhouses, but does not want to put any money into anything until he is forced to.