**** foul odor ****

[dutchev]

We have been fultiming for 4 yrs. and have a 2007 fifth wheel. We don't have a sani-flo system so i use a Flush King gate valve to back wash my black water tank. After every dumping i refill the back tank with fresh water at least 2 times. I have a clear elbow so that i can see it flowing. My question is that lately i have been getting a foul odor from the toilet when we flush. I also use the odor liquid every time. Whats up with this?

[wolfe10]

randallb wrote:
Make sure you turn off your bathroom fan before you flush. The number one cause of smell being pulled back in to the bathroom is a running fan when the toilet valve is opened.
Randy

And, if your fan is reversible, have it on INTAKE when flushing.

[randallb]

Make sure you turn off your bathroom fan before you flush. The number one cause of smell being pulled back in to the bathroom is a running fan when the toilet valve is opened.
Randy

[punomatic]

oldmattb wrote:
We had a similar symptom. The rubber seal between the toilet and the pipe had failed, literally sliced open through years of use....One flush and the odor returned, robust and nasty.

Waste from the toilet was leaking...[and running down the floor of the wet bath to the drain.]

...we reinstalled the toilet with a domestic-style neoprene seal from [Amazon].

Problem gone.

X2

[TechWriter]

Before you check the seals, vents, add a venturi, or remove the toilet, pour some bleach down the toilet. This will be a short-term solution while you work on a long-term fix.

[oldmattb]

We had a similar symptom. The rubber seal between the toilet and the pipe had failed, literally sliced open through years of use. We would clean the whole area and park for storage and the smell would be gone. One flush and the odor returned, robust and nasty.

Waste from the toilet was leaking around the seal and under the tile in the bathroom. A flush would add moisture and reactivate the yuck that was already there.

On our last trip, we removed the toilet and treated the area with an enzymatic odor eliminator. We cleaned the toilet and the area thoroughly. (We also eliminated a bidet attachment from the previous owner.) Then we reinstalled the toilet with a domestic-style neoprene seal from Home Depot.

Problem gone.

Matt B

[Old-Biscuit]

I don't use chemicals......always found their smell unpleasant.
And other than a whiff when flushing due to open line to toilet we don't have foul odors. I find chemicals just a marketing hype

You stated "...lately i have been getting a foul odor from the toilet when we flush."

Odor only when you flush:
*Exhaust fan(s) running will pull odor up from tank when you flush (open line from toilet to tank)

*Toilet drain line to tank has build up of stuff (use a toilet wand on end of garden hose and blast line)

*Toilet pedestal is nasty (inside portion between toilet bowl and floor flange)---would need to remove toilet, take outside and blast away on it.

[azdryheat]

In hotter weather I find that doubling the dose of holding tank chemicals works at keeping the odor at bay. The chemicals are also approved for gray tank use. Bottom line - if there is an odor, you aren't using enough of the stuff.

[Bumpyroad]

I think I would invest in a black tank sprayer which would help clean out your tank.
bumpy

[2oldman]

I don't know what the problem is. I've rinsed the tank a couple times in its 12 years to install a new toilet, and the odor, although not pleasant, was not overwhelming.

If you bought used ( sorry.. 'new to us'), perhaps there's something dead in there.

Oh, and I never use chemicals.

[tkcas01]

Wolfe10 has good advice. I was going to vote for the autovent under the sink in the bathroom. On my rig, it only has one roof vent and both holding tanks tie into it. If yours is the same this could explain how flushing would affect a vent on the sink drain.

As he said, make sure the roof vent is not blocked. As he said, I'd then check the tanks where the pipes connect. I finally solved a similarly frustrating issue and it was a tiny leak around where the built-in tank flush nozzle was attached. Odor found its way up into the coach.

[wolfe10]

I would suggest your approach is incorrect. You will never succeed in making a gray or black tank contents "smell good" or "not smell".

Instead, concentrate in keeping the odor in the tank from getting into the interior. This is done by keeping air pressure in the tank lower than that inside the RV. There are several venturi-based devices that mount on the roof vent for the tank that help.

Also, check the air admittance valve under the sinks. Their rubber can dry out and allow gray tank odor into the interior.

Of course, there could be a physical reason for the change. For example, the vent pipe may have slipped down into the tank, a bird or insect nest may be blocking the roof vent, etc.