Sewer smell when using full hook up

[tlw3989]

I do not use parks much with full sewer hook ups...last night after hooking up the sewer hose and opening just the 2 gray water tank valves, we had a bad sewer smell inside. We had just arrived so only a little sink water was in the tank and the shower tank was empty.

Even though there was no odor before opening the dump valves, I ran water to make sure there was water in the sink and shower traps to stop the odor but it did not stop so I just closed the valves and the odor slowly went away. I can manage opening the valves for an ocasional tank draining but thought I should be able to stay there with the gray tank valves open.

Am I doing something wrong or might there be a vent probelm with my RV...which is still under warranty.

BTW, RV is a 2012 Avalanche 345TG FW.

Thanks!!

[Ron]

On our Montana, the shower does not have a trap as it should, but we do not have a problem with sewer gas. This winter I will be putting a trap in I don't know why they left it out. We leave all our valves shut until dumping is needed to prevent the possibiity of sewer flies getting into the gray tanks and trailer as alot of folks have had that issue. Check the shower location for a trap, probably your problem area. Run a little water down your lav and listen in the shower drain to see if you can hear water trickling into the tank............Ron

[hankaye]

tlw3989, Howdy;

Not sure how your's is set-up, it may be the kitchen
sink vent. open one tank valve at a time to see (smell),
which tank is the offender. If it's the Galley tank look under
the sink to see if there is a short section of pipe sticking up
into the space maybe 1.5ft. it should have a slotted cap
on top with a spring loaded rubber disk inside, that's
the Galley tank vent. the rubber may have become mishapped
and not sealing properly.
If that is ok, then put a 'trap' in the sewage hose itself.
Some folks use a empty coffee can. The smell could have
been the sewer itself venting thru your tanks and out the
vents in the trailer roof.

hankaye

[happytrails]

I have had similar issues and I believe it is related to traps. Once I close the dump hose valve all issues go away. What I did is bought a flush king look-alike from amazon and put that on and leave the galle gray tank valve open and the flush king closed. My galley gray valve is located under the slide so it's a pain to get to with the slide out. This way if the tanks are getting full I can just pull the flush king valve. Works like a charm. If you add a trap or traps you have to remember to fill them up once your camper is set up so no air can come through. Most people probably run the water for a few minutes anyway to flush the lines out a little. I know I do. That would fill your trap(s). The other thing that may be going on is (and I don't know if it's something that actually happens) if the sewer line for the camp ground has any back pressure which could potetially blow enough pressure into your traps to clear them and then you get the smell again.

As far as the flush king look-alike I would go with the original flush king and pay a little more. My friend has the real deal and it works better. The flush king has a built in 45 degree bend where mine is just straight but I already owned a 45 degree bend with flush connection. The 45 comes in handy sometimes when your back end is sitting a little low to the ground.

[Cool Canuck]

I do not use parks much with full sewer hook ups...last night after hooking up the sewer hose and opening just the 2 gray water tank valves, we had a bad sewer smell inside. We had just arrived so only a little sink water was in the tank and the shower tank was empty.

Even though there was no odor before opening the dump valves, I ran water to make sure there was water in the sink and shower traps to stop the odor but it did not stop so I just closed the valves and the odor slowly went away. I can manage opening the valves for an ocasional tank draining but thought I should be able to stay there with the gray tank valves open.

Am I doing something wrong or might there be a vent probelm with my RV...which is still under warranty.

BTW, RV is a 2012 Avalanche 345TG FW.

Thanks!!
I believe what happens is the sewer gas from the dump system travels up through your grey tanks and continues up through the tank vents. It then drifts into to your ceiling vents or just around the RV in general. My solution is to put a raised area in the sewer hose. That acts like a P trap.

[tlw3989]

Thanks for all the pointers and suggestions! I did track the galley vent to behind the kitchen drawers and the shower vent to the bathroom sink cabinet. I do have 1 plumbing vent on the roof and guess it is for the black tank. Hard to tell if these are working or not but did use the sewer hose trap suggestion using a piece of firewood and it worked like a charm! I did notice that most other RVs in the campground also had this manmade hose trap.

I will certainly use this trick for the rest of my RV life…thanks again to all!!

[CincyGus]

I just leave the dump valves closed until it's time to dump. Prevents any food from accumulating and helps things break up if they are in water rather than maybe getting rinsed with the water in the sink and maybe ending up sitting in the tank because there was not enough water used to move them to the drain.
Those tanks are designed to be dumped when they a significant amount of water in them, not with a half gallon or slightly more run as someone is washing greese and food particles off a plate. Just my two cents but something to consider.

Going to pull the handles every 2-4 days and letting it drain and then shutting them closed seems easy enough for me.