Advantages of Boiling
– Highly effective against biological contaminants.
– Simple and requires no special equipment beyond a heat source.
– Improves taste by removing volatile organic compounds (VOCs).
Disadvantages of Boiling
– Requires fuel and a heat source, which may be limited in an emergency.
– Does not remove chemical contaminants or particulates.
– Can be time-consuming.
Chemical Disinfection: Chlorine and Iodine
Chemical disinfection is another effective method for purifying water, particularly when boiling is not feasible. Chlorine and iodine are the most commonly used chemicals.
Chlorine
Household bleach (unscented, with 5-6% sodium hypochlorite) can be used to disinfect water.
How to Use Chlorine
1. Filter the water to remove large particles.
2. Add 8 drops of bleach per gallon (4 liters) of water.
3. Stir and let the water sit for at least 30 minutes.
4. If the water is cloudy or very cold, let it sit for 60 minutes.
5. The water should have a slight chlorine smell. If not, repeat the process.
Advantages of Chlorine
– Effective against bacteria and viruses.
– Widely available and inexpensive.
– Simple to use.
Disadvantages of Chlorine
– Less effective against protozoa like Giardia and Cryptosporidium.
– Can leave an unpleasant taste and odor.
– Chemical concentration must be carefully measured.
Iodine
Iodine tablets or tinctures can also be used for water disinfection.
How to Use Iodine
1. Filter the water to remove large particles.
2. Add iodine tablets according to the manufacturer’s instructions, or use 5 drops of 2% tincture of iodine per quart (liter) of water.
3. Stir and let the water sit for at least 30 minutes.
4. If the water is cold or cloudy, let it sit for 60 minutes.
Advantages of Iodine
– Effective against bacteria, viruses, and some protozoa.
– Portable and easy to use.
– Suitable for short-term use.
Disadvantages of Iodine
– Not suitable for long-term use due to potential health risks.
– Can leave a strong taste and odor.
– Less effective against Cryptosporidium.
– Not recommended for pregnant women or individuals with thyroid conditions.
Filtration: Removing Particulates and Pathogens
Water filters physically remove contaminants by passing water through a porous medium. Filters vary in their effectiveness depending on pore size and the type of filter media used.
Types of Water Filters
Pump Filters
Pump filters use a manual pump to force water through a filter cartridge. They are effective at removing bacteria, protozoa, and particulates.
Advantages of Pump Filters
– Effective against most biological contaminants.
– Portable and suitable for backcountry use.
– Can filter large volumes of water.
Disadvantages of Pump Filters
– Requires manual effort to pump water.
– Filter cartridges need regular replacement.
– May not remove viruses without additional treatment.
Gravity Filters
Gravity filters use gravity to pull water through a filter cartridge. They are easy to use and can filter large volumes of water without manual effort.
Advantages of Gravity Filters
– Requires no pumping or electricity.
– Suitable for filtering large quantities of water.
– Effective against bacteria, protozoa, and particulates.
Disadvantages of Gravity Filters
– Slower filtration rate compared to pump filters.
– Bulky and less portable.
– May not remove viruses without additional treatment.
