If you get sewer odors in your camper, there is something wrong with the vents for the tanks.
There will be some folks that will suggest that "chemicals are bad!", but you will have to experiment with what works for the long term sewage storage you are dealing with. It will be important to know what the location that you will be taking your sewage to will allow in their system. Some places have a "no formaldehyde" rule, and might insist you use RV/Marine TP.
The two tubes are more than likely low point drains for draining the fresh water system for winterization.
You need to find someone, a friend or relative, that is familiar with RVs to help you with this stuff, or start taking digital pictures and learn to post them here so that you can get more precise help.
ORV 19B Full Timer, '14 Ram 2500 Diesel and a GSD. This signature updated, August 13, '16.
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