Boiling is the safest method of purifying water. Bring water to a rolling boil for 10 minutes, keeping in mind that some water will evaporate. Let the water cool before drinking. It will taste better if you add oxygen prior to drinking the water. This can be done by shaking the water or pouring it back and forth between two containers.
Chlorination uses liquid chlorine bleach to kill microorganisms.
Use only liquid bleach that contains 5.25 percent sodium hypochlorite, no soap or fragrances, and no active ingredients other than hypochlorite. If the water does not smell of chlorine at this point, add another dose and let stand 15 minutes. Purification tablets release chlorine or iodine. They are inexpensive and available at most sporting goods stores and some drugstores and supermarkets. Follow the package directions.