Water can be purified by boiling for five to ten minutes.
Iodine is added to water as a solution, crystallized, or in tablets. The iodine kills many—but not all—of the most common pathogens present in natural fresh water sources. Carrying iodine for water purification is an imperfect but light weight solution for those in need of field purification of drinking water. There are kits available in camping stores that include an iodine pill and a second pill that will remove the iodine taste from the water after it has been disinfected.
Chlorine-based bleach may be used for emergency disinfection. Add 2 drops of 5% bleach per liter or quart of clear water, then let stand covered for 30 to 60 minutes. After this it may be left open to reduce the chlorine smell and taste.
Water filters are also used to make water potable. These filters are usually small, portable and light (1-2 pounds), and filter water by working a hand pump. Dirty water is pumped via a tube through the filter, then out into another flexible tube and directly into a water bottle. These types of filters work to remove bacteria, protozoa and cysts, all of which can cause disease. These water filters should not be confused with devices or tablets that are water purifiers. Water purifiers satisfy higher EPA standards, and also remove viruses, such as hepatitis A and rota virus, among others.