The Lifestraw, purifies the water before it reaches the lips.

LifeStraw is a water filter designed to be used by one person to filter water so that they may safely drink it. It filters a maximum of 1000 litres of water, enough for one person for one year. It removes 99.9999% of waterborne bacteria and 99.9% of parasites.The LifeStraw Family, a larger unit designed for family use, also filters out 99.99% of viruses.
LifeStraw includes LifeStraw and LifeStraw Family, which are complementary point-of-use water filters designed by the Swiss-based Vestergaard Frandsen for people living in developing nations and for distribution in humanitarian crisis. LifeStraw Family filters a maximum of 18,000 liters of water, providing safe drinking water for a family of five for up to three years
[SOURCE:http://en.wikipedia.org/wiki/LifeStraw]