Black tank smell in coach

[What_s_Next_]

I have had our coach for 7 years now and every once in a while while driving I get a really bad smell coming into the coach. It smells like the black tank is venting into the coach. The weird thing is it doest smell bad in the bathroom. I always flush out the tanks really well and add chemicals to the black and gray tanks. Any help is appreciated.

[dougrainer]

Bikeboy57 wrote:
Doug,

You always give good and experienced commentary, but in this one case I have to respectfully disagree with you. In my own coach, we would experience black tank odors in the coach if the potty were flushed while driving. I stopped up and blocked all the air admittance valves, and then on to blocking all vent fans. Still we would get the smell from time to time. It did seem to be related to windy conditions. A little more research and design understanding on my part showed that flushing the potty left an open path to the waste tank. If the pressure inside the coach was less than waste tank, then the odor would migrate into the coach.

I spent the 50 bucks to install two of the wind vane ventilators on the two roof vent pipes. No more smell.

You are correct. But the OP was NOT flushing the toilet in transit. I never stated that there would be NO odor if flushing in transit. There is no way that a gray tank odor could migrate thru the toilet when flushing it if EACH tank had its own separate vent pipe to the roof. Maybe possible IF they combined the 2 roof vent pipes to 1 vent on the roof. Not all RV's have a separate vent pipe for each tank on the roof. You do indeed have a natural lower pressure in the motorhome while in transit and can easily pull in outside smells. Doug

[guamuchil31]

best quick fix.replace ur original pluming vent caps with cyclone vents it works really good and is really cheap to do.

[Bikeboy57]

Doug,

You always give good and experienced commentary, but in this one case I have to respectfully disagree with you. In my own coach, we would experience black tank odors in the coach if the potty were flushed while driving. I stopped up and blocked all the air admittance valves, and then on to blocking all vent fans. Still we would get the smell from time to time. It did seem to be related to windy conditions. A little more research and design understanding on my part showed that flushing the potty left an open path to the waste tank. If the pressure inside the coach was less than waste tank, then the odor would migrate into the coach.

I spent the 50 bucks to install two of the wind vane ventilators on the two roof vent pipes. No more smell.

[dmcgiffin]

I had the same problem....short answer..it is the check valve. Simple fix...unscrew the old, screw on the new. Problem fixed.

[Cmore12]

When we experienced it, an excessive amount of chemicals toned it down. Later I read an open driver's sliding window (at cruising speed) can allow black tank fumes to pulled back inside. I'll try that next month on our first drive of the spring. I hope that's wrong; aiming for fresh air and getting, well, not-so-fresh is disappointing.

'12 Tiffin Allegro RED 34
Misc toads

[bdarenberg]

This device does both tanks. I have tank penetration kits for DIY installation. It's on a timed cycle where it feeds ozone rich air into the tanks, which is rapidly broken down in the presence of the wastewater. No odors from the vents, so odors cannot find their way back into the coach. Powered by 12 volt DC less than 7 amps. Not only does it remove odors it also kills most all pathogens in the waste making it safe to handle while dumping. I also make air purifying/sanitizing device which do not produce ozone to rid the coach of odors from cooking, pets, smoking and destroys airborne pathogens such as viruses.

[RayChez]

If you drive with a window open, it will create a vacuum. It will suck the water out of traps and pull the odor off the grey and black tanks.

Before you go out on any trip run a little water on the sinks, shower, washer and the toilet. Drive with the windows closed. You should not have any smell in your coach.

[TechWriter]

bdarenberg wrote:
I have come out with a new product. I have a machine that diffuses Ozone into the grey and black water tanks..

I can maybe see an ozone system in a grey tank, but a black tank???

Please give more details.

[bdarenberg]

I have 30 years as a sanitation tech on both yachts and r/vs. The idea is to kill the odors before they go out the vents. There are a lot of factors that can draw the odors into the coach, plus grey water odors escape through the drains. By diffusing the ozone in the manner I use ozone is broken down rapidly it's not really in contact with any parts rubber or otherwise. I've been running one for over six months...no odors..no failures..of either the machine or toilet parts.

[wolfe10]

bdarenberg wrote:
I have come out with a new product. I have a machine that diffuses Ozone into the grey and black water tanks..no odors and as an added benefit it kills off most of the bacteria and pathogens in the waste making it safer to handle.

Got to ask-- who cares of it smells in the tank. The whole purpose of the way RV plumbing is done (house plumbing as well) is to isolate the smell from the interior of the coach, NOT make the **** smell good.

BTW, Ozone is really tough on rubber parts.

[bdarenberg]

I have come out with a new product. I have a machine that diffuses Ozone into the grey and black water tanks..no odors and as an added benefit it kills off most of the bacteria and pathogens in the waste making it safer to handle.

[iamcanuck45]

I had the same problem whenever I opened driver's side window. Everything was OK. I had to remove the toilet to put down some new flooring, and noticed that the toilet rubber seal stunk like H... When I replaced the toilet, I used a wax seal. Problem solved.:B

[ArchHoagland]

We noticed several years ago if we kept the three roof vents open while driving the coach would start to smell.

We now keep all the roof vents closed while driving.

[subtroll]

It been a couple of years so my memory may not be complete but I remember our National came with an omni-directional cap on the vent pipes. When I had the Venturi vent installed the technician reported that the roof top pipe was not properly connected to the pipe leading up through the roof, ie there was a gap an inch or so below the top of the roof. Exactly how the odors were getting into the coach is not clear but he sealed the vent pipe and I think whatever slight vacuum the venturi creates in the black tank is a good idea.