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Air and smell from toilets when flushing

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tmoon2000

New member
We purchased an Alliance Paradigm 370B last April and have had continuous issue with sewer smell coming up from the toilets when the valve is open during flushing. It's almost like there is a vacuum / negative pressure issue. We have tried every chemical on the market, and that's not really helping, it's the actual air coming up from the bowl when flushing. Why would this be engineered for air to travel up from the toilet and not down into the toilet when flushing? This happens from both the toilet in the master bathroom, and from the toilet in the living room.

Anyone have suggestions? We spent a lot of money on this 5th wheel and having to deal with this smell filling the living areas is really annoying.

Thank You!
Tom & Jenn
 
T

tmoon2000

New member
Grassjohn said:
A pretty good tech tip from Alliance:


My 385FL had symptom #1, the tank vent pipes on the roof were cut short, allowing sewer gas to accumulate in the “attic” and get sucked into the air conditioner and sent into the coach. Easy to check - remove the vent caps and see if the pipes go all the way up into them.
Click to expand...
Hi, we checked that before, vent pipes are good length, no smell from AC or attic, stench rushes out of toilet when flush valve open
Thanks
 
M

Mpmizell

New member
We just purchased a 2024 385FL. When flushing the master toilet smell comes up when the vent is off. Having to dump every other day to keep sm down. Never had problems with other rv we lived in full time. Any suggestions as to why this is happening. Also hav replaced both vent caps
 
J

Jeanne

New member
We are having the same issue. We clean and clean the tanks each time we dump until the water runs clear?. We also picked up our 2025 370 FB in April. It’s really awful.
 
BryanValRox

BryanValRox

Elite Member
Jeanne said:
We are having the same issue. We clean and clean the tanks each time we dump until the water runs clear?. We also picked up our 2025 370 FB in April. It’s really awful.
Click to expand...
Take a look at the attached sheet. You should validate item number 1.
You should also try to snake something down the black tank vent to ensure that nothing has it plugged up or restricted.
It really shouldn’t be that complicated, if odor is coming backup the toilet during flushing, it would certainly seem to me that the vent pipe is somehow restricted , not cut to the proper height or is covered over by roof material.

 
Oregon_Camper

Oregon_Camper

Forum Admin
Staff member
Spend a day cleaning your black tank.
  1. Empty and flush. Fill tank with ~40 gallons of water...put in 4x the amount of tank treatment. Let it sit for 24hrs
  2. Empty and flush tank again. Fill with 30 gallons of water...empty agian
  3. Now, from this point going forward, use 1/2 a bowl of water if you're not on city water....a FULL bowl of water if you're on city water. Use the foot flush to fill the bowl after each flush, with correct amount.
  4. Always use the foot flush to fill the bowl...with the tank flapper closed.
  5. Never leave bowl flapper open to add water to the tank
  6. More water in your tank is the solution.
We had a slight sewer smell in our 340RL when we flushed as well. Once we started doing this method, the smell never came back.
 
R

RoadJunkie

Member
It is difficult to solve this problem, in the long run, by covering up the odor with chemicals. The system is choosing the toilet opening as the path of least resistance to vent. The reason needs to be determined. We had a rig that was having an odor problem, but I applied spray foam sealant between the vent pipe and the "attic" and that solved that issue. I'm not saying that is your problem, however. Maybe drain and flush the tank and add some water down the vent to check for blockage and to see if it reaches the drain?
 
L

Lantley

Prominent Member
Maybe worthwhile to go up on the roof and make sure the vent cap in on the vent pipe that protrudes through the roof.
 
F

Funkgirl

New member
I’d check the tank roof vent for a blockage and make sure the flush seal has water covering it. I’ve fixed similar smells by cleaning the vent and adding a little more water.
 
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