We drink from the fresh water tank, but it is filtered twice. There is a filter for all water coming into the MH, and a separate filter and tap for drinking water. We also do a chlorine treatment at the beginning of the season.
We rented a MH from Cruise America many years ago and I asked if the water in the tank was OK to drink. He said that he wouldn't, there could be frogs growing in there for all we know. If you get your water from a known source (not always possible when camping) then you should be OK.
You probably need to test your body's systems periodically anyway. What could go wrong?
