Bad Smell

[mpz1430]

Good Morning, we cannot figure out why there is a bad smell all the time in restroom. Sometimes it lingers in the entire RV. Worse when we flush. Please advice.

[whitexc]

Smells as though you have a vent problem on the black tank. Can you carefully check the roof vent, maybe pop a cap off and check with a flashlight?

[nomad297]

Do you leave your black tank valve open all of the time, or do you leave it closed and dump the tank after it is almost full?

Bruce

[mpz1430]

Thanks for the reply. Will definitely check today.

[Flybob]

Check to see if you have the Dometic model 300 toilet. There is a known issue with them. The other possibility is the air admittance valve under the sink may be stuck open. (see below)

[PhilFromMaine]

Sounds like your system is partially venting in the bathroom. Think of a wood stove that doesn't vent properly. You constantly have that lingering smell of smoke in the house. There is a hypothetical mathematical formula that takes into account your tank size, resistance of the wall areas, and height of stack. Your system is out of sync.

Causes, as others above have noted, could be obstructions in the stack, open valves when hooked up to camp site sewer systems, or air leaks in the system.

Your toilet should seal shut with a water layer in the toilet. Does your toilet hold water when not in use? Do you keep the cover down when you flush? Every time you flush you are breaking up the air flow to the vent and in effect making the bathroom the exit point for some of the sewer gases. A good water seal and keeping the toilet cover down should be your first area of investigation.

Hope this helps.

[sdelam]

I have a similar issue. Takes a couple of days to start to smell but once it does the only fix for me is to dump it. Smell will clear up after that.

Back story though... a few years ago I arrived home from a trip to find the grey water tank missing, FR failed to install the screws in the bracket holding it in place. The repaired it under warranty but ever since I have had vent issues. Really makes me wonder is the vent seal did not get messed up when the grey tank fell/ripped out. I just have not got around to dropping the black tank to see whats going on yet.

[rsdata]

Many people have complained about urine odor from their Dometic model 300 plastic toilet, which has a known design defect... could this be an issue?

[chriscowles]

Originally Posted by mpz1430

Good Morning, we cannot figure out why there is a bad smell all the time in restroom. Sometimes it lingers in the entire RV. Worse when we flush. Please advice.

Stick a camera (phone?) in the back of the toilet base, facing down. Take a pic of the interior.

Look at the pic. Is there a pool of liquid? If so, you have the Dometic 300 toilet problem. A seal leaks.

Depending on age, it may be covered by warranty. YMMV on the resolution offered by the manufacturer.

Some of us got replacements. Others, including myself, were able to upgrade to a 310, paying only the difference in retail price. Still others got lip service.

[oxcamper]

One other possibility, which happened to us, is that the black tank shifted on it's mounting brackets and the discharge pipe partially slipped out of the tank, allowing odors to come up from underneath, and black water to drip into the underbelly.

[TitanMike]

One question. Are you using any holding tank chemical to keep the smell down IN the tank?

I use the brand "Odorlos" and add after each dumping. No smell even after flushing and normal "toilet use odor" has been exhausted by the fan.

One thing I learned over the years is that tank odor can be seriously increased with hot weather. It sometimes requires more holding tank treatment when things get hot than when it's more temperate.

Also helps to use the tank flush (if equipped) to make sure the tank is really clear of solids after dumping.

[Herk7769]

I had this issue with my new (then) Flagstaff. The worker who made the roof penetration for the black tank vent made the hole too big and the Dicor that sealed the penetration had over time dropped into the overlarge hole.

The factory solution was to pack the hole with insulation and reseal around the pipe. This fixed the problem of tank smell dropping into the camper from the roof.

This can be exacerbated when using the bathroom fan as it will suck air out of the camper and accelerate in incoming odors from the vent stack.

[rsdata]

One other possibility, which happened to us, is that the black tank shifted on it's mounting brackets and the discharge pipe partially slipped out of the tank, allowing odors to come up from underneath, and black water to drip into the underbelly.

I just changed from a #300 to a model 310... and yes it would be easy to have the down pipe from the toilet shift out of the tank hole, OR the tank hole to shift away from the toilet discharge pipe...

Easy enough to check... loosen the two toilet base nuts on the bolts, ( might also have to take off fresh water supply hose at the rear) and pick toilet up a bit to have a look... just have a fan blowing fresh air into the bathroom area when doing that...

[doanshop]

I had same problem removed vent cap found wasp nest in vent after I removed nest took garden hose flushed down vent pipe problem gone .