Rain water is all chem trail water and could be full of drugs, it is not a real option at this point.
I know waterwise took their non electric water distillers off their sales list for the rest of this tear for some weird reason, they are small enough to take and go. I have non electric water distillers but they are large.
As far as a filter? Your local army surplus store or the boat stores etc...that have devices that can turn ocean water into drinking water. Then ad pure oregano oil to that water or the tree iodone extract would be some ideas.