I use a 3-Stage filter from the water filter store. stage 1 is a particulate 10 micro reusable filter, stage 2 is a KDM 5 micron, stage 3 is a .09 micron absolute ceramic. I then fill my fresh water tank which I sanitize every couple months and use my water pump to keep great pressure. I have had no issue with any water. Stage 1 and 2 have a 1-3 year life span and stage 3 has a 5-7 year span.
http://www.rvwaterfilterstore.com/