Hello hoping someone can help. We are camping till next Sunday. We are getting odor from the vent under bathroom sink . Never had this happen before. I closed the gray tank added allot of camp chem then drained when full. No smell. Well opened back up and smell back. Is it possible I'm getting odor from there sewer line. It gets worse when using vent fan. Anything you guys think I can do or check. Thank you
So you mean top of vent under sink. Is it a carbon filter of some sort. And thank you
Yes, the top vent under the sink. It's a one way valve that allows air to enter the drain line so water won't be siphoned from the sink trap when draining the sink but blocks gasses from the holding tank entering the room (when it is working; they are subject to failure). If that valve fails in the open position, it will allow gasses from the holding tank to escape into the room. If it fails in the closed position (rare, btw), water will be siphoned from the trap and gasses can escape into the room through the sink drain. Any home center or hardware store should have AAVs although they may refer to it by a regional slang or brand name. Take the old one with you when you go looking for a replacement.
Most likely the AAV is sticking open a little bit. There are two versions of it. I think the RV industry uses the cheaper one. The other version is much better, and is permitted for us in homes. It is just threaded on to the black pipe. While you are at camp un thread it, check it. Put it back on. When you get home, it might need to be replaced. If it does, do a little research to determine which style you really should replace it with.
I do leave the gray tank valve opened but I always put a "dip" in the sewer hose to act as a trap to keep the CG sewer system isolated from the TT tanks.