Forum Discussion

StirCrazy's avatar
StirCrazy
Moderator
Feb 13, 2023

Ok who knows there toilet/black tank systems

Ok so the used camper I bought three years ago has and issue I havent been able to track down yet. so the toilet works perfect, tanks are good (I had to change the guts of the dump valve as it was weeping)
but I still have an issue

so when I am driving and pull over to use the washroom or when we get to the campground and I go to use the washroom right away it smells like a outhouse. this goes away and it is fine for as long as we are camping.

so it only happens when I am driving, the vents are closed when I am driving so its not getting sucked in the roof vents, the seal in the toilet holds water, and there is a little water in the bowl when I am driving.

any ideas where I should look next??

thanks
Steve
  • StirCrazy's avatar
    StirCrazy
    Moderator
    Feb 14, 2023
    opnspaces wrote:
    Yes probably an air admittance vent AKA cheater valve the is not longer a one-way valve. Available at Lowes or Home Depot for around $10


    there all p traps. and why would that be on the black water system?
  • StirCrazy's avatar
    StirCrazy
    Moderator
    Feb 14, 2023
    enblethen wrote:
    Water sucked out of drain traps
    No water in drain traps
    Vent under washroom sink stuck open, if equipped. air admittance style vent


    all p traps still have water, that was my first thought..

    I'll have to go look again I have never seen an atmittance valve in this camper.

    Steve
  • RLS7201's avatar
    RLS7201
    Explorer II
    Feb 13, 2023
    If the Air Admittance Vent doesn't fix your issue. There is another possible reason for the stink inside your RV. When going down the road, the inside of the RV goes into a negative pressure, caused by the large flat area in the rear. This allows the pressure differential to induce a stink in the RV. I replace the caps on the roof vents with sanitary Ts, to put the tanks into the same pressure as the inside of our MH. Or you can purchase the rotating roof vents. Rotating roof vents.

    Richard
  • Grit_dog's avatar
    Grit_dog
    Navigator
    Feb 13, 2023
    ^Bingo. Or black vs gray smell is typically totally discernible to all but the most oblivious sewer dumper. Lol

    Does it happen all the time or only if traveling with partially to very full black tank?
    Only had 3 “RVs” now but all of them were the same, both older and fairly new units. If black tank was fairly full and we’d travel a distance, like any sustained highway driving, the black tank odor would come into the camper.
    Not the P traps or gray.
    And no other odor issues.
    Seal around bottom of toilet like mentioned recently could be it.
    My solution was to dump what I hoped I could have dumped 100miles sooner, lol.
  • opnspaces's avatar
    opnspaces
    Navigator II
    Feb 13, 2023
    Before your next trip pour a cup of pine sol down your kitchen sink drain. Then run the tap and wash the pine sol out of the trap and into the gray tank. When you get to your destination you'll know if the smell is coming from the black or gray tank. (credit to Doug Rainer on this idea)
  • WNYBob's avatar
    WNYBob
    Explorer
    Feb 13, 2023
    I just saw a post this week where someone solved his issue with black tank smells. He changed the floor seal and the toilet.!
  • MFL's avatar
    MFL
    Nomad II
    Feb 13, 2023
    enblethen wrote:
    Water sucked out of drain traps
    No water in drain traps
    Vent under washroom sink stuck open, if equipped. air admittance style vent


    I agree, it doesn't sound like the black tank could be the issue.

    Easy to fill drain traps, including sinks and shower, when stopped. Does smell go away?

    Jerry
  • opnspaces's avatar
    opnspaces
    Navigator II
    Feb 13, 2023
    Yes probably an air admittance vent AKA cheater valve the is not longer a one-way valve. Available at Lowes or Home Depot for around $10

About Technical Issues

Having RV issues? Connect with others who have been in your shoes.24,201 PostsLatest Activity: Feb 19, 2025