This book is written from the perspective of backpacking, camping, exploration and other back country travel activities in which one must rely on local water sources. The information is equally applicable to post-disaster and emergency survival situations and environments.If you want to drink the water and not get sick from it, this is everything that you will ever need to know. If you are ever caught in a disaster zone and have to drink questionable water, this is everything that you will need to know to make it safe.If you have traveled or spent time in the back country drinking the local water you may have become familiar with traveler's or Wilderness-acquired diarrhea. The severity can range from insignificant to vacation spoiling to serious. The common pathogens and methods of spread are discussed.An essential part of water supply and management is accurately estimating one's water needs. The basic information on how to do this is presented. It is easy to underestimate water requirements.The effects of dehydration and heat injuries are discussed along with treatment and re-hydration. Methods of locating and collecting water in all environments are discussed.The various water treatment and purification methods and technologies along with their capability and limitations are compared and discussed. The author is an experienced hiker who has spent time in the boundary waters of southern Ontario, the Missouri Ozarks, the trails in the Big Bend area of Texas, the deserts and mountains of New Mexico and the trails of the Pacific Northwest.