Steri-pen was the solution to getting enough drinking water while spending 3 weeks in South America. The pen (about the size of a small flashlight) kills 99.9% of bacterial, viruses and protozoa in water in moments. A small UV light sterilizes either a liter or .5 liter of water while you stir your glass or water bottle. Perfect solution while traveling when often the only safe thing to drink is soda or alcohol. A good way to get those 8 cups even while traveling.
Got mine from Amazon.com