We have always been good at using porta-paks in our RV, which has done a good job of keeping the black tank from smelling. So I had to figure out what I was still smelling as I sat at the dining table!

To keep our black tank from smelling in the RV, we have always used porta-packs. I always put one in there every time we set up at a campsite, again every time the tank is emptied, and I add one at the end of a camping trip before we store it. I didn't use to add one at the end, but then I realized sometimes I would get in the RV weeks or months later and I could smell the tank. I started making dropping one in there as we parked it to store it a habit and it seemed to help get rid of that issue. We don't use anything fancy, we use standard porta-packs that you can get at Walmart or Amazon. They seem to work fine and now that I use them as I mentioned, we don't have an issue with smelling the black tank.

However, it got to where we could smell "something" as we would sit at the dining table. It kind of smelled like urine, but didn't smell like the black tank. I couldn't put my finger on it, but I felt that it had to do with our grey tank system, which was close by under the trailer. We purchased some Camco TST Grey Water Odor Control and used it as per the package directions.  It doesn't take a lot, so the bottle that you get will last a while. This stuff worked great and got rid of the odor I kept smelling, but was unsure of the exact source. 

There are things that get built up in the grey tank, like oils, food debris, etc., that can make it smell. This grey water odor control worked great. It has a lemon scent and it got rid of the smell that was coming from the tank. We keep it with our supplies ever since, but we don't have to use it often. Every once in a while when I start smelling that odor again, we grab the grey water control and use some, and then it's gone again. This is a good supply to keep in the RV and even if you don't smell the grey tank, use it every once in a while to keep things cleaned in there. 

I'm happy to say that between using porta-paks and this grey water odor control it is rare that we will have an unpleasant odor in the RV. These products work well to keep odors away, which is really important when you are in such a small space. 

Update: July 2024 - We are camping and there is no store nearby to purchase the grey water odor control, but we have the smell back! So what I did is have my husband empty the grey tank. Then I put one cup of Dawn platinum down there and let the hot water run (it didn't even get to a half a tank and I stopped it). Then we let it sit for about 30 minutes. Within about 15 minutes the smell was gone. This method worked just as good as using the commercial odor control. So if you have the odor control on hand, great. If not, grab some Dawn platinum from a local store and it will do the same thing. Worked great! The smell is gone again.