how many drops of bleach to purify a gallon of water
Add 8 drops (almost one-eighth U.S. teaspoon) of regular liquid bleach per one gallon of water to be treated. Mix thoroughly and let stand for 30 minutes (important). Then, smell the water. If the water has a faint smell of chlorine, then it is okay to use. If you cannot detect any chlorine odor, add another 8 drops of regular liquid bleach.