thanks for input on my problem. I have a 2013 Via. Have noticed an odor in motorhome for first time. I know it is coming from the black tank. It has been very hot where we are (90's) and I notice the odor on about the 3rd day after dumping the black tank. It is definitely worse when AC is running and is worse in bathroom. almost seems to be coming from under the sink. there is a cover in floor under sink to allow access to water pipes---seems to be coming from this area. I am concerned that there is a small leak in a vent or something allowing odors to be pulled into motorhome when AC running---getting worse as black tank sits for a few days. Does this seem reasonable?? Once I dump tank --- odor goes away for a few days then returns. I do use chemicals in tank and doubled amount recommended due to hot weather. thanks for input on this
black tank odor in motorhome
- Thread starter rthompson
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Fcranger
Well-known member
Have had the same problem for a long time tried 2 of those Camco Cyclone vent caps on the roof seems to be a lot better don't know how good there going to hold out because they swivel 360 degrees put one on the black water vent and gray water vent on the roof seems to be a lot better 
kjansen
Well-known member
Try using more water when you flush. Keeping plenty of water in tank seems to help, but you will have to dump more often.
John Canfield
Site Team
Welcome! I would look at your plumbing diagrams and find/inspect the venting just to be sure you don't have a fitting coming loose.
Gary RV_Wizard
Site Team
If the smell is strongest under the sink, it is probably NOT coming from the black tank. There is an air admittance (anti siphon) device for the gray water waste line under the sink. It is basically a rubber flap that is supposed to stay closed except when their is suction in the waste line. Sometimes they get "tired" and don't seat well, allowing the gray tank odor to escape. It is easily replaceable (its just a slip-on cap on the vertical pipe under the sink) and available at any plumbing supply department or store.
Most people don't realize that gray waste tank typically has as much or more odor than the black and often very similar in aroma. It's rotting food waste in either case.
Most people don't realize that gray waste tank typically has as much or more odor than the black and often very similar in aroma. It's rotting food waste in either case.
ArdraF
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The odor might be worse if you have fans turned on that suck the air up through either the toilet when flushed or the traps under the sink and shower. It's commonly from the gray tank so make sure you don't allow much in the way of food particles to go down the drain because that rotting food stinks. Also, adding double the chemicals probably won't help. Many people on this forum use no chemicals at all. The advice to add more water when flushing is good because it prevents the dreaded "poop pyramid" which increases the likelihood of odors. Use the Search button above to find many previous discussions on this subject.
ArdraF
ArdraF
John Canfield said:
I agree. I had the same issue. After numerous complaints to my service shop, they checked the black tank. Turned out the vent pipe was stuck too far down in to the tank. The odors and materials were therefore backing up in to the living space.
Otherwise, when moving fill your tank at least 1/4 full with water, put in 1/2 bottle of bleach and a cup of dishwashing soap. The motion of the RV will help scrub the tank and limit the odor problems.
Our best to you and let us know how it turns out.
garyb1st
Well-known member
Gary RV Roamer said:
Gary, we have a pvc pipe with a vented cap under the bathroom sink. Sounds similar to what you're talking about. It is maybe 1-1/2 inch in dia, and screws on. I tried to unscrew it by hand and it didn't budge. I'm afraid to use a wrench for fear I might crack the pipe below the floor. What are my options?
Regarding the gray vs black odor, I can attest to that. The gray can generate some foul order.
GaryB1st
catblaster
Well-known member
Tape a sandwich bag over it and see (smell) if the odor goes away. also if the bag inflates then it is leaking air into the room.
Gary RV_Wizard
Site Team
Great tip, Will!
Fittings on PVC are just slip on (not threaded), but they can still jam. Option #1: Use two wrenches, one to support the pipe while the other turns the fitting. A strap wrench may be sufficient to keep the PVC pipe from breaking, but you can (carefully) use a pipe wrench or channel lock pliers instead. Option #2: Unless you are positive the fitting is threaded on, use a block of wood and a heavy hammer to tap the fitting upwards. Move the block around the circumference of the pipe and against the lip of the fitting, a few taps in each place until it breaks loose. Use a heavy hammer so that you get a good amount of momentum without having to swing hard (and wild).
garyb1st
Well-known member
Jeff in Ferndale Wa
Well-known member
Gary RV Roamer said:
If it were the grey water, and normally get worse after a few days, could it be something as simple as the sink not being used, and water evaporating out of the P trap?
Gary RV_Wizard
Site Team
I see the threads in the photo, but what about the flange underneath? These vent caps are intended to be replaceable. Looks like the working part threads into the flange. The top could be unscrewed from the flange, and the flange may be slipped off the pipe if it's not glued. In any case, the two wrench technique is the standard way to handle threaded fittings on pipe.
I couldn't find that exact model of ProVent on their website, but a similar one looks as though there may be a bolt on top. Maybe it has to be loosened to unscrew? Take a look at the ProVent Trap Guard model: http://www.trapguard.com/
I couldn't find that exact model of ProVent on their website, but a similar one looks as though there may be a bolt on top. Maybe it has to be loosened to unscrew? Take a look at the ProVent Trap Guard model: http://www.trapguard.com/
ArdraF
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Yes, that definitely happens when an RV is stored for a period of time or the utilities are not used. It happens to sink and shower traps as well as the washer-dryer trap. I suppose it could even happen with an outside shower although I'm not sure about that because I don't remember how they're constructed. That's why it's a good idea to use your RV to its fullest. I'm always amazed when someone says they don't use their shower or their washer because those features are why we bought the RV in the first place. They are meant to be used....
ArdraF
garyb1st
Well-known member
One of the prior owners put a black putty like substance around the base of the pipe. It's soft and rubbery. I'm wondering if they had a broken pipe and tried to fix it with the black stuff. If so, I'm probably in for a lot of odor or a rather expensive repair.
Gary RV_Wizard
Site Team
Or maybe he thought he was sealing out a smelly air leak when it was really elsewhere? Guess you will have to remove the caulk to see...
