1 Answer

HEAT!

While camping, there's rarely a fresh water source available, causing many campers to bring their own bottled water. If it happens that the trip is extended, and the fresh water source is depleted, do not resort to drinking creek or river water, even if it appears perfectly clear. Water from creeks, rivers, puddles or standing pools contain bacteria, e-coli and possibly lead, aluminum, or zinc. Bacteria-infected water can cause horrible diseases such as typhoid fever, dysentery, and cholera. Even if there's no clean water, there are still ways to have clean, safe drinking water by treating it.
Coffee filters and other such filters are good for cleaning leaves, bugs and bark from water, but they are ineffective in killing bacteria and removing metals. Specially designed filters can now be purchased for filtering drinking water while camping, but some of these filters only clean up the taste and smell of the water, so know what you're getting before making a filtration system purchase.

Boiling water kills bacteria, and water that has been exposed to air for a length of time, usually contains bacteria. Simply heating the water then cooling it will not make it safe to drink. Water should be brought to a rapid boil for at least 10 minutes, then stirred while cooling, before drinking. Stirring puts some air back into the water to improve the taste somewhat.