I filter nearly all natural water sources which is very handy and if it keeps me from buying water. There are places I would definitely not get water from even with filtering, like run offs from the highway or industrial areas. I don't quite trust my water filter enough for chemicals.
I just like the ability to get safe drinking water from almost any natural water source whether it's a puddle or an intermittent creek. Maybe I may have to start filtering water piped-in also. I am really wanting to buy one of these
http://www.rei.com/product/737349/ka...p-water-filter for in-camp use or for increasing my carrying capacity for dryer regions.