We take bottled water to drink and I take a gallon or two with me to make a pitcher of tea or koolaide. I've used the water from the site filtered through the camper to make coffee with no trouble.
I'd planned to drink the water from the site faucet this year at Fall Creek Falls in Tn, but the water was rusty and dirty looking. I washed dishes with hot water that had been filtered through the camper and we brushed our teeth with it. Nobody got sick, but it was too nasty to drink and I'm glad I'd brought water with me.
Even filtered through the camper system I was worried about drinking it.
Lesson learned on taking extra water with me "just in case"