Not necessarily (Though I do not know the park in question many TT parks use wells. no treatment if the water meets quality standards which vary from state to state). Others use city water (Treated as a general rule).
That said. As you move from location to location,, If it's more than a very short distance. water changes.. On my dad's farm when a well collapsed and we had to drill a new one about 75 yards away the water was different.
This can cause issues. Most notably Montezuma's Revenge. or as I call it. Frequent flyer syndrom.. Till your body adjusts to the new supply.
Fact.. Normally in the summer I fill up at one Campground (12 well system) and stay there 2 weeke. re-fill and head to a TT park about an hour away. stay there 2 weeks. never touch a hose. Back to the first and re-fill..
After a summer of doing that it got cold so I dropped by Marshall MI for a new factory rebuilt converter and on to Upstate SC..
That 80 gallons I filled up with the day before Halloween lasted me till Thanksgiving AM.. the next 80 gallons lasted a week.. Frequent flushing syndrome. after that it was back to re-filling every 3 weeks.