We use the onboard tank or CG source for everything. There is a whole RV filter between the tank and pump, and I have a hose filter that is used for all the water we fill the tank with or get from a CG faucet. We usually keep the MH ready to travel, so some water stays in the tank at all times. If we have an extended time between trips, I might add a few tablespoons of Clorox before I complete the fill.
An added point came to light a few days ago...We foster and adopt special needs kids. During our most recent training session the agency we work through said any family with special needs kids needs to keep a 3-day emergency kit including clothing, first aid, food, and water...among other things. Our stocked MH contains everything on their list. If we have to "bug out" (a term frequently used on M.A.S.H. 4077) we have almost everything we need ready to go. Where practical we have duplicate medical equipment on board, but need to load medicines. We might need to stock some perishables, but non-perishable food, clothing, first aid supplies, and water are pretty much already on board, and at least some level of gas is in the tank.
Ken, Judy, and the Angels--2005 Fleetwood Southwind--2008 Cargo Trailer--2003 EZGO Golf Cart