When I full timed I stayed 2 weeks in one park 1 or 2 in another. After my wife died a full tank was at least 3 weeks of water.
NOW: one of the parks (always a 2 week stay) used city water and the city over chlorinated.. Made my morning cuppa taste like it was brewed with diluted clorox. Found if I filled the tank..... Chlorine quickly dissipated. (Water supply Chlorine will do that if not pressurized) So I'd fill the tank when I pulled into that park and again when I pulled out to the 1 week park and not even hook up at the 1 week park.. The night he temps hit 11. I was glad to be "not hooked up" I can tell you.
Summers one of the 2 week parks has "Nasty" (Lots of grit) water. .. Now my filter handles it but .. Why clog the filter when I can tank up before leaving the other park and again when I return.
Sulfur.. My Parent's had high sulfur water on their retirement farm... Letting it set helps..
Filters help as well I've been in parks where I could not drink the water without filters.. Even low end filters worked in some of them.
Reverse Osmosis is the filter of last resort. Most expensive. but most effective as well.. Can (depending on how good) produce near pure water.
Resin Distillery can as well