Boiling water is a widely recognized and accessible method for making water safer to consume. This technique has been employed for centuries, particularly in emergency situations or when the quality of a water source is uncertain. It offers a straightforward approach to disinfection.
How Boiling Works to Purify Water
Boiling water purifies it by using high temperatures to inactivate pathogenic microorganisms. The heat disrupts their structural components and essential life processes, such as denaturing proteins, rendering them harmless. This process is more accurately described as pasteurization rather than sterilization, as it targets organisms harmful to humans rather than eliminating all microbes. For effective purification, water should reach a rolling boil. Boiling effectively eliminates most common waterborne biological contaminants. This includes bacteria like Escherichia coli (E. coli), Salmonella, Vibrio, and Campylobacter species. It also inactivates viruses such as Hepatitis A and Rotavirus, and protozoa including Giardia lamblia and Cryptosporidium parvum, which are also effectively destroyed by boiling.
Impurities Boiling Cannot Remove
While boiling is effective against many biological contaminants, it has limitations and does not remove all types of impurities. Chemical pollutants are generally not affected by boiling. These can include pesticides, herbicides, industrial solvents, and pharmaceuticals, which are heat-stable or do not evaporate with water. As water boils and evaporates, these substances can become more concentrated in the remaining water. Heavy metals, such as lead, mercury, and arsenic, are also not removed by boiling. These elements have significantly higher boiling points than water and remain in the liquid phase, potentially increasing in concentration as water volume decreases through evaporation. Similarly, nitrates, often found in water due to agricultural runoff, are not reduced by boiling; their concentration can actually increase as water evaporates. Total dissolved solids (TDS), including various minerals and salts, are also not removed by boiling and can become more concentrated.
Step-by-Step Guide to Boiling Water Safely
To safely purify water by boiling, first address any visible cloudiness. If the water appears cloudy or contains debris, pre-filter it using a clean cloth, coffee filter, or paper towel to remove larger particles. This initial step helps ensure the boiling process can effectively target microscopic pathogens without interference from suspended solids.
Next, bring the pre-filtered water to a rolling boil, meaning it should be bubbling vigorously. Maintain this rolling boil for at least one minute at sea level. For altitudes above 6,500 feet (approximately 2,000 meters), boil the water for at least three minutes to account for the lower boiling point.
After boiling, allow the water to cool naturally before consumption. Store the purified water in clean, sanitized, airtight containers to prevent recontamination. Food-grade plastic or glass containers with tight-fitting lids are suitable for storage.
Boiled water can sometimes taste flat due to the loss of dissolved gases like oxygen and carbon dioxide during the heating process. To improve the taste, pour the cooled water back and forth between two clean containers several times. This aeration process reintroduces air, making the water taste fresher. Adding a small pinch of salt to each liter of boiled water can also help enhance its flavor.