They have ways of sanitizing the water when they restore service in the spring,, Same methods you use on your RV in fact.
The major problem with camp ground water is this: There is no pure water in nature, It is not possible for water, naturally, to be pure, not even rain is pure water.
And what is worse, the water where YOU are is different from the water wher I am, different mineral content, different bacterial content. Perhaps some other differences as well.
Now you are used to the water where you live, your body tolerates it and you do not have a problem... Same with me and the water where I am.
BUT.... If you come visit me, or I you.. Good chance of the body reacting to the change in water with a good case of Montezuma's Revenge.
The solution.. Well usually the solution.
A simple Activated Charcoal filter can take care of most of the diferences and make is so you will not find yourself getting frequent flyer miles on the porcelain airline. Adding and advanced filter (Brita, PUR, et-al) improves that even more.
On this coach all water runs through activated charcoal.. Then drinking water gets a Brita as well.
You can also get whole-house filters that are far more advanced than the simple one I use.