Stumped by tank odor

[Part-time]

This last weekend was like all of the rest for the last two years. Camp have fun, come home dump the tanks and clean out the trailer. Rinse and repeat. This time after the drive home we had an odor coming from the black tank in the bathroom. It wasn't there upon departure but when arriving home it was there.

After dumping the tanks I started going thru what I know to do, check the toilet to see if its holding water in the bowl, checking the air admittance valve on both sinks. All are in working order.

So now what?

[egwilly]

I would start by adding some enzyme tank liquid, fill the tank and let it sit for a couple of days and drain a few times with the San T Con flusher. The tank liquid needs time to "digest".

Add about 12 oz of dawn and fill, and let it sit overnight an flush some more.

This can only happen if you are not cleaning out enough and solids are still there. You already checked the vent to the roof right?

[TXiceman]

A gray tank can smell as bad as the black tank. There is an air admittance valve in the drain under the sink. They can sometimes leak and stink like mad.

These can be picked up at most hardware/plumbing places. As a temporary fix, you can wrap the thing with tape to stop the smell.

Ken

[RVingNow]

We sometimes forget to be sure there's water in the laundry p-trap.

[Ljwt330]

Is there a sink in the same room with the toilet? If so, I agree that the odor is probably from the grey tank, through an air admittance valve. Same with the laundry.


Without knowing how your rig is laid out, the grey tank is the most obvious culprit. However, if the toilet is in a room by itself, that focuses the issue on the black tank and toilet. Still, if there was water in the bowl there should be no odor. If the seal between the toilet and floor is tight, there should be no odor. Driving a long distance with a nearly full black tank could produce odors that do not exit the vent pipe due to a separation between the pipe and the roof exterior. Odors could also escape through a broken toilet to floor seal. Rare, but possible.


Let us know the location of the toilet relative to the vanity sink or any other grey tank fixtures.

[Part-time]

The odor is gone now. I added enzymes and flushed it twice. I also added enzymes to both grey tanks. My only theory is that one of the p traps may have siphoned off while we were driving home. We had a head wind of 15 to 20 mph. All of the air admittance valves are in working order. Roof vent is clear too.
Thanks for the replies.