The surest way to ensure you have clean drinking water is to boil the water. Put contaminated water in a pail and bring the water to a boil. Leave it boiling for about a minute. At the end of a minute the water will be ready to drink,. Lot of people keep the water boiling for longer. This does not help as the water will not get any hotter, it will only evaporate. At higher altitudes, water takes longer to boil, so keep it boiling for about five minutes. Visit http://OTASurvivalSchool.com for more information.