A cheap screw on Britta filter for the kitchen faucet will remove most "plastic" tastes if you are sensitive to them. I attach it after I de-winterize in the Spring and remove it at the end of the season. Works great b/c we don't have a large enough refrigerator for the pitcher-type Britta filter.
Always fill from the well at home and use fresh water for everything.
EDIT: has ANYONE ever found a salesman who actually camps!? In 20 years of asking I never have.... even spoke to designers/RV builders who do not use their own products! I find that the service guys are more likely to be campers than the flashy salesmen. Just saying.