Boiling water is a straightforward and dependable method for purifying water, especially when a water source’s safety is uncertain or during emergency situations. This accessible technique eliminates many harmful contaminants, making water safe for consumption.
How Boiling Purifies Water
Boiling purifies water by utilizing high temperatures to inactivate or destroy harmful microorganisms. The intense heat damages the structural components of pathogens, disrupting their cellular processes and denaturing their proteins, which are essential for their survival. This process is more accurately described as pasteurization rather than sterilization, as it targets organisms that cause harm to humans.
Waterborne pathogens such as bacteria (e.g., E. coli, Salmonella, Shigella), viruses (e.g., Hepatitis A, rotaviruses), and protozoa (e.g., Giardia, Cryptosporidium) are effectively eliminated through boiling. Even at temperatures below boiling, many of these microorganisms are inactivated; for instance, protozoan cysts begin to be pasteurized at 131°F (55°C).
Step-by-Step Guide to Boiling Water
To begin the purification process, first address any visible cloudiness in the water by filtering out large particles or sediment. This can be accomplished using a clean cloth, paper towel, or coffee filter to strain the water. Once the water is visibly clear, pour it into a clean pot or kettle suitable for heating.
Next, place the container over a heat source and bring the water to a rolling boil. A rolling boil is characterized by rapid, continuous bubbling from the bottom of the pot. Maintain this rolling boil for at least one minute if you are at an elevation below 6,500 feet (2,000 meters). For altitudes above 6,500 feet, extend the boiling time to three minutes to compensate for the lower boiling point of water at higher elevations.
After the required boiling time, remove the water from the heat source and allow it to cool naturally. Boiled water can sometimes taste flat due to the reduction of dissolved gases like oxygen during heating. To improve its taste, you can aerate the water by pouring it back and forth several times between two clean containers.
What Boiling Doesn’t Remove and Storage Tips
While effective against biological contaminants, boiling water does not remove chemical pollutants or sediment. Substances such as heavy metals (e.g., lead, mercury), pesticides, nitrates, and microplastics are not eliminated by boiling and may even become more concentrated as water evaporates. Therefore, boiling alone is insufficient if the water source is contaminated with these chemicals.
After purification, safely storing boiled water is important to prevent recontamination. Use clean, sanitized, food-grade containers with tight-fitting lids. Glass or plastic bottles previously used for beverages are suitable options, but avoid containers that held chemicals or milk.
Label the containers with “Drinking Water” and the date of storage. Store them in a cool, dark, and dry place, away from direct sunlight or substances like gasoline or pesticides, as plastic can be permeable to vapors. Properly stored boiled water can remain safe for consumption for up to six months.