Sewer/black tank smell inside trailer

motogeek wrote:
I did not know that water in the p traps acted as a vapor barrier. I will make sure to fill the p traps before it gets parked.

That IS their only purpose in being...fill it with RV antifreeze so it doesn't evaporate (as fast) or freeze.

I have trouble about once a year with mine and found that its something to do with the vent lines. I get up on the roof and run some water down the vents, clears it up. These are grey water, not black. Still don't know the reason but tried it as a suggestion from a buddy and it works.

Thanks for all the advice. I forgot to ad there is no smell in the bathroom of the trailer so that might eliminate the toilet. There is a vanity sink and the kitchen sink that can vent bad smells directly into the rig. The bathroom only has a shower and a toilet and the door is kept closed. I did not know that water in the p traps acted as a vapor barrier. I will make sure to fill the p traps before it gets parked. And just for good measure I will buy a toilet wand to clean the black tank. Plus the air admittance valves might need replacing as suggested. Thanks again.

Not a large chance, but you might want to check the toilet at the floor level or just below the floor. We had black tank odor and it turned out to be the toilet leaking slowly at the floor level. The leak never appeared above the floor or below the trailer.

Did not discover it until we pulled the toilet up.

I do what "N-Touble" does every now and then as well.... Just to make sure I get the black tank clean. After I put my treatment in the black tank, then I also re-fill the treatment bottle with water to get the residual treatment out, and pour half of the bottle into the bathroom/kitchen sinks.... "P" traps can start smelling if that water sets there to long. P traps are designed to keep the smell out for every day use.... not if they set up for awhile.

There's likely a turd teepee that has built up under the can from previous owner that doesn't get flushed by simply dumping the tank. As mentioned get a wand, or what I like to do is fill the tank about 1/2 water then drop a few bags of ice in and drive it down a long twisty road. The ice will break down the teepee and clean off any sensors. Take it to a dump station and watch all the pooh soup that comes out through your clear elbow.

Repeat this a couple of times then fill with a few gallons of water + treatment and see if your problem persists. I always leave some amount of water in my black tank as you don't really ever want it dry.

As suggested..replace the 'air admittance valve(s)' They have probably dried out (rubber flapper) in that '07 rig.

They are screwed onto a short stub pipe just after the sinks 'P' traps.
When they don't close, grey tank odors can be pulled inside trailer..grey stinks as bad as black.
Available at most hardware stores.....couple of bucks. Just hand tight...no tools needed

When the barriers are properly working no waste tank odors can come back inside RV even IF black tank was full of poop

Toilet bowl holds water...vapor barrier
'P' traps holding water....vapor barrier
Toilet floor flange sealing...mechanical barrier
Air admittance valves closing properly....mechanical barrier

Tank vent clear........dissipates odors out above rig/prevents pressure build up so odors can't be pushed inside rv.

Look under kitchen & bathroom sinks for these....

The 'gray' tank can smell just like that also. Especially if the previous owner put a lot of food stuffs down the drain and didn't clean it regularly.

I use one quart of a lemon cleaner to 'clean' the tank out. Found at any grocery store. Pour it down and fill with water and drain. Repeat if necessary.

Also check to make sure your p-traps in sinks are full with water. At least one sink might drain into the black. No water in p-trap will let black tank smell come into your RV.

You just are not getting the tank clean put a hose down the toilet and clean the tank or get a wash wand

Check or replace your air admittance valve(s) at your sinks.
Also make sure you leave a little water in the bowl (helps complete the seal).