To purify water: • Using water purification tablets. (Follow the directions provided.) •Placing five drops of 2 percent tincture of iodine in a canteen full of clear water. If the canteen is full of cloudy or cold water, use 10 drops. (Let the canteen of water stand for 30 minutes before drinking.) •Boiling water for one minute at sea level, adding one minute for each additional 300 meters above sea level, or boil for 10 minutes no matter where you are.