RVs all have a fresh water tank. When you rent one, they will often tell you not to drink that water. That’s because the tanks are being filled up in all sorts of random places, out of the control of the rental company, and while it’s probably safe, they don’t want to promise it, nor disinfect the tank every rental.
I recently got a small “pen” which you put in a cup of water and it shines a UV light for 30 seconds to kill any nasties in the water. While I have not tried to test it on infected water, I presume that it works.
So it seems it makes sense to me to install this sort of UV tube in the fresh water tank of RVs. Run it from time to time, and particularly after a fill, and be sure the water is clean. Indeed, with an appropriate filter, and a 2nd pump, such an RV could happily fill its water tank from clear lakes and streams, allowing longer dry camping which should have a market. Though of course the gray/black water tanks still will get full, but outside showers and drinking do not fill those tanks. A urination-only toilet could also be done if near a stream or lake.