Introduction
Water purification is essential for survival in emergency situations. This guide covers various methods to ensure safe drinking water, including boiling, chemical treatments, filtration, and natural purification techniques. Each method has its advantages and limitations, and understanding them can help you choose the best approach based on your specific needs and circumstances.
Boiling Method
Boiling is one of the most reliable methods for killing pathogens. Bring water to a rolling boil for at least 1 minute (3 minutes above 6,500 feet elevation). Boiling kills bacteria, viruses, and parasites but does not remove chemical contaminants. For heavily polluted water, boil for 20 minutes to eliminate typhoid spores. Use a container and a heat source. Avoid using plastic containers as they may release harmful chemicals when heated.
Pre-Filtering
Before boiling, filter water through a cloth or t-shirt to remove large particles and debris. This step improves the boiling process and extends the life of your containers.
Chemical Treatments
Chemical treatments are effective for disinfecting water. Use unscented bleach (2 drops per liter), iodine (5-10 drops per liter), or commercial purification tablets. Chlorine tablets are quick-acting but may leave a slight taste. Iodine solutions have a longer shelf life but may degrade over time. Avoid using bleach on cloudy or murky water without pre-filtration. Always follow manufacturer instructions for tablets.
Bleach Storage
Store bleach in a cool, dry place between 50-70°F (15-21°C) to maintain potency for 3-6 months. Label containers with the purchase date and dosage. Use a first-in-first-out rotation system, and repurpose expired bleach for laundry or garden pest control. Avoid storing bleach with ammonia to prevent toxic gas formation.
Calcium Hypochlorite (Pool Shock)
Calcium hypochlorite (pool shock) is ideal for long-term water purification. Dissolve 1 teaspoon (0.25 oz) of granular calcium hypochlorite (78% concentration) in 2 gallons of water to create a stock solution. Mix 1 part stock solution with 100 parts contaminated water. Let sit for 30 minutes before consumption. Aerate the water by exposing it to air to reduce any residual taste.
Filtration
Commercial filters (e.g., Lifestraw, Katadyn) use ceramic or charcoal to remove bacteria, protozoa, and some viruses. Pump-operated or straw-style filters are effective for immediate use. Pre-filtration with cloth removes large particulates and improves filter longevity. Filters meeting federal standards (blocking particles larger than 0.02 microns) are highly effective. Replace filters according to manufacturer guidelines.
DIY Filters
Construct layers of large gravel, sand, and activated charcoal in a container. Pour water through the filter to remove particulates and improve taste. This method is effective for removing large particles and some chemical contaminants.
Natural Purification Techniques
Solar Still
Construct a solar still using plastic sheeting, a container, and a flat rock. Place the container in the ground and cover it with plastic sheeting. Place a flat rock in the center of the plastic to create a low point. As the sun heats the ground, water evaporates and condenses on the plastic, dripping into the container. This method is effective for desalination and purification of contaminated water.
Boiling Pot Distillation
Use two containers (one larger than the other) and a flat lid. Place the smaller container inside the larger one and secure the lid. Pour contaminated water into the larger container. Heat the setup until water evaporates, condenses on the lid, and drips into the smaller container. Collected water is free from bacteria, salts, heavy metals, and chemicals. This method is more labor-intensive but removes more contaminants than boiling.
Summary
Water purification is crucial for survival in emergency situations. Boiling, chemical treatments, filtration, and natural purification techniques are all effective methods to ensure safe drinking water. Each method has its advantages and limitations, and understanding them can help you choose the best approach based on your specific needs and circumstances. Always store treated water in clean containers and avoid reusing containers that held iodine to prevent residue buildup. Regularly check and rotate your water purification supplies to ensure they are ready when needed.