Wilderness Manuals - Water Procurement - Describes how to find, purify and store water. Features illustrations and links to related topics. - http://www.wildernessmanuals.com/manual_6/chpt_7/2.html
The Ranger's Digest: Filter and Purifying Water - Describes how to filter and purify water. - http://www.therangerdigest.com/Tips___Tricks/Filter_and_Purifying_Water/body_filter_and_purifying_water.htm