Sewer odor issues

[firestation12]

You have received a lot of great suggestions from the forum group. I also endorse the use of the Zep product as recommended (in both the gray and black tanks) in post #3. I also have had to replace the air admittance clapper under the sink. The vent openings on the roof have tops, that were other parts I replaced as a holistic approach to smell control. I also add Dawn dish soap to shower, kitchen, bath lav drains with each tank draining along with the zep product. One thing not mentioned in the original post was the model toilet installed in the problem camper. Thetford has long been known to leak waste product internally and emit foul odors. If you have a Thetford, consider replacing it. One last suggestion to consider is, what things when used in the camper, create a negative pressure which can draw odors back into the camper past the air admittance valve, the toilet valve if not sealing, the HepO valve (If you have one that is defective). Things like a Fantastic fans in the kitchen or bathroom, kitchen hood vent, windows open on the lee side of the camper when windy outside, or leaks in ac ducts, create a negative pressure. How does an ac duct leak cause a negative pressure (suction) to occur? Any air that escapes on the pressure side ducting into the attic space, causes an ingress of an equal amount of air from any number of places, to enter the camper anytime the ac fan is drawing air into the return. I would suggest you consider doing all the many ideas given in this thread, as well as keep doing the great job described in post #1. Not directly related to the smell problem, that has happened this past year was a slow drain of shower water. A leaf blower was used to easily restore active draining. Once cleared, adding Dawn soap into the drain, then another application of pressurized air from the leaf blower into the drain, worked magic.

[Cbrandt79]

Thank you for all the good comments and suggestions! Today I am going to replace the toilet seal at the floor and replace the emitter in the kitchen. I think I have replaced just about everything. Time will tell if we fix the ‘stink’.

[HDLimitedGuy]

I have a 2014 3901RK. We would get the smell in the rig whenever we would dump either black tank. The smell was being sucked in through the 3 AC units. Started shutting them off when I dumped. Problem solved.

[High5er]

You mentioned you're full timers. We full time as well and leave our gray valves open when the overnight temps are above freezing (I close them periodically to allow them to fill and drain to minimize the nastiness inside them and the hose to the ground). I found that if left open, the draining black can create a vacuum that empties the P traps in your sink/shower drains. The result is wide open pipes to the sewer/septic and those gasses are free to flow inside. If you're leave the gray open most of the time, I would start closing it every time you drain your black tank.