Or .... every time you fill your tank, whether at home or at a campground, you can play it real safe and do two things:
1. Always screw an inline RV filter onto the end of the hose - where it enters your fresh water tank refill opening.
AND
2. Always at the end of the hose where you screw it onto the refilling faucet - hold the hose end straight up and carefully dump 4-6 oz. of chlorine into the hose from a paper cup, wait a second for it to run down into the hose a bit, and then screw it onto the faucet.
We sometimes do both of the above and sometimes do neither of the above, but just in case to be ultra safe .... we NEVER drink the water from our RV's "fresh" water system. We only cook, bathe, and clean with it.