We're going to have 2 fresh water tanks - on either side of the bus - linked together by a common line which will feed the pump (and also act as a drain). The tanks are inside the bus.
Tank 1 is being vented through the gravity fill cap. So no worries there. But that leaves tank 2. I'd really rather not buy another vented gravity-fill cap, as I only need one fill. But I don't know how else I can route this vent to the outside, above tank level, and also protect it from contamination/debris/a-holes.
I have 2 tanks, one above the other. The gravity feed port fills the top tank that also gravity feeds the bottom tank. The hose connecting the bottom tank will vent into the top tank and out the fill spout. If you have a line connecting your 2 tanks it should vent as well.
I Thank God That He Gifted Me with Common Sense