When my parents had their travel trailer (1963-1973), we all drank from the on-board water tank. Back then, the tank was a steel-galvanized tank, the water lines were copper tubing, and it was run with air pressure. No pumps, except the bicycle pump to put pressure into the tank. And we're talking water from every source imaginable.
Fast forward, Pop-up ownership and TT ownership now since 1999 (17 years now), and always drink from the on-board tank. If you are afraid to drink from the tank, then there's something wrong. Your water system originally is manufactured with new tanks and pipes. A simple draining after every use and a simple sanitation every now and then will keep them clean. Your on-board water system is probably more sanitary than that store bought bottled water!
If you are getting your water from a public source, then it has to be approved and inspected, and pass specific tests. It won't kill you! Now ... getting your water from a bucket out of a lake ... that's a different story. But sheesh.... really!