So are chemical contaminants
. Geez what kind of rain do you guys get?
I have successfully used my bimini with a hose connector into a gauze strainer and no filters and while at sea the water gathered this way has been delicious.
I would probably agree with the serious filtration if you're in a harbour or near an industrial area but at sea . . . . not necessary. Just a quick wash of the catchment device (my bimini) to get rid of any bird droppings (the only contaminants at sea and even then rare), dump the first few gallons and away you go.