Holding tank odor

Thanks folks. Have tried all the great suggestions. Inlet pipe is definitely too far into tank. I suspect a poor glue connection of the riser to the roof vent. The odor does not come from near the commode, sink or drains. It is just
"there" The logical solution to me is to
shorten the inlet pipe.or drill it full of vent holes with my 90 degree drill adapter & short bits! What do you think?

I had the EXACT same problem with my previous Fleetwood Flair AND our new Winnebago Vista. Don't understand why the 'drop pipe' has to go so far down into the tank. What I have gotten into the habit of is, after using the toilet for 'number 2', I'll refill the bowl with water to the top (holding the pedal partially down) and then flush the bowlfull of water. This seems to disperse the solid waste and prevent the buildup at the drop pipe. Also, the extra water seems to help when you dump the black tank. If you let it build up too much, it can get solid enough down there to prevent any further waste from entering the tank and you will have what looks like a stopped-up toilet. Nasty. Before it gets that bad, you'll probably notice the flush goes down with air bubbling back along with the familiar stink. Since we adopted the 2nd full bowl water flush procedure, we have not had the problem. Still do not understand the 'long pipe'...

Mvpmich wrote:

TNGW1500SE wrote:
I don't see how the pipe would cause an odor even if it is "to far down" in the tank. Does the odor come from the toilet of could it be from the sink? Some RV's a plumbed so the bath sink goes into the black tank. Check for a vent under the bath sink

If the vent pipe is too far down in the tank it could be below the fluid line and therefore prevents air from escaping. The problem is probably twofold, 1) the tank needs to be flushed and cleaned and possibly sanitized to rid any long standing or built up materials and 2) better exhausting from the vent stack.

I had similar problems after I dumping and thought the tank was empty and clean only to find residual waste as well as back drafting while driving. I installed a Camco Cyclone swivel cover on the vent stack that allows the wind to suck out the odor either while driving or stationery. There are other types including the DIY "t" mentioned that will give you the same results.

He's talking about the pipe from the toilet to the tank being to far down.

Shouldn't the toilet seal in all the odor? It does on mine. If I wanted to smell the black tank, I'd have to go on the roof.

PS: I have no plans to do so ;)

I have a feeling that your waste pipe from the toilet may be too long and the only thing that should do is reduce your time between dumps. You may have to measure your black tank height and the compare that figure with the distance from the bottom of the waste to the bottom of the tank.

I had a similar problem with my newly purchased Winnie and I did a really great flush, cleaned and lubed the flappers in the AAVs, replaced the seal in the toilet(the bowl wouldn't hold water)and no more odor. I have a Tornado flush system. I also have a hose flush fitting on the elbow from the knife valve.

No odor.

Good luck.

TNGW1500SE wrote:
I don't see how the pipe would cause an odor even if it is "to far down" in the tank. Does the odor come from the toilet of could it be from the sink? Some RV's a plumbed so the bath sink goes into the black tank. Check for a vent under the bath sink

If the vent pipe is too far down in the tank it could be below the fluid line and therefore prevents air from escaping. The problem is probably twofold, 1) the tank needs to be flushed and cleaned and possibly sanitized to rid any long standing or built up materials and 2) better exhausting from the vent stack.

I had similar problems after I dumping and thought the tank was empty and clean only to find residual waste as well as back drafting while driving. I installed a Camco Cyclone swivel cover on the vent stack that allows the wind to suck out the odor either while driving or stationery. There are other types including the DIY "t" mentioned that will give you the same results.

I don't see how the pipe would cause an odor even if it is "to far down" in the tank. Does the odor come from the toilet of could it be from the sink? Some RV's a plumbed so the bath sink goes into the black tank. Check for a vent under the bath sink

In the bathroom department of Home Depot or Lowe's there are PVC 'T's. I think they're 1 & 1/4". Climb on the roof, remove the dome style covers over the two vent pipes, and put the 'T's on the ends of the vent pipes. The open ends front to back. This will help remove odors either driving or parked. Then do what BS suggests since you'll be up on the roof anyway.

I suggest flushing the black tank more often and use a black tank deodorant. And I agree with B.S. in Mich. check that vent pipe.

Have you checked if the tube fro the roof vent is plugged? If that goes too far in the tank it will give odors.