Not sure of the year of the RV. I am having very strong odors after flushing and I have cleaned the black tank with EVERYTHING. I have had it flushed and all seems well, but in a day or two it is back to being foul. I’m thinking it is the filter or siphon but I do not know where to locate these and pinpoint which it is. Why does my black tank always smell? —Heather, Wilderness Advantage Extreme Edition
I would suggest trying Thetford’s “Tank Blaster” product as it will get rid of most of what I call the “Bad Bugs,” which are anaerobic bacteria that create those rotten egg smells.
Next, I would suggest looking for your vent. The black water tank has a vent pipe that comes up through the coach and is designed to allow air in so there isn’t a vacuum when dumping the tank. Most go up through an interior wall and are seen on the top of the unit. However, if the pipe comes up in a kitchen area with a countertop, it can’t make it all the way to the top so they cut it off under the counter and use a siphon cap, which we call a cheater vent. These are designed with a gasket that allows air to draw in but does not let the smell seep out. However, they go bad all the time! Find out where your vent is and also make sure it is installed on the tank. I have found them to break off or come loose and the odor comes up through the coach.
RVtravel.com publisher Chuck Woodbury swears by the Siphon 360 vent, which draws air from the black tank out the top of the RV. He tells me that since he replaced his cheap factory installed vent with the Siphon 360 he has no problems with odors.
You might also enjoy this from Dave
I want to clean my black tank valve but I can’t find it
I am living in my motorhome because Hurricane Ian flooded my house. I can’t find the black water tank valve. However, I know where the handle is to open and close the valve, but I want to find the valve itself so I can either clean it or replace it. I have looked all over the place for it. I can’t find it in the service center like the other valves. On another topic, I wonder if I can refill the propane tank without taking it to a dealer. Thanks for your help. —Thomas, 2017 Winnebago Vista 29E