Travelers who are heading to remote places to camp or hike or staying in locations with unknown water quality may need to disinfect their drinking water. Bottled water is a convenient solution, but the plastic bottles create an ecological problem. Some methods to ensure safe drinking water are described below.
Most germs die quickly at high temperatures. Water that has been boiled for 1 minute is safe to drink after it has cooled. If no other means of water treatment is available, an alternative to boiling is to use tap water that is too hot to touch, which is probably at a temperature between 131°F (55°C) and 140°F (60°C). This temperature may be adequate to kill pathogens if the water has been kept hot for some time. Travelers with access to electricity can bring a small electric heating coil or a lightweight beverage warmer to boil water.
A variety of filters are available from camping stores. Most have filter sizes between 0.1 and 0.4 microns, which will remove bacteria from water but may not remove viruses. Reverse osmosis filters remove bacteria and viruses and can also remove salt from water, which is important for ocean voyagers.
Tablets or packets of powder can be bought at camping stores to disinfect water. These usually combine chemical disinfectants (such as chlorine or iodine) with a substance that makes the water clear and improves its taste. Follow the instructions on the package closely—you may need to wait several hours until all the germs are killed. Household bleach can also be used to disinfect water.
Ultraviolet (UV) Light
Portable units that deliver a measured dose of UV light are effective to disinfect small quantities of clear water. However, this technique is less effective in cloudy water because small particles may shield germs from the light.
In emergencies, sunlight in the UVA range can substantially improve the quality of water. In cloudy weather, water must be placed in the sun for 2 consecutive days.
Solar disinfection is not effective on cloudy, opaque water. If the headlines in a newspaper cannot be read through the bottle of water, the water must be clarified before solar irradiation is used.
Learn more about germ size, filtration type, and disinfection techniques.