Boiling pool water is not a safe way to purify it for drinking. While boiling effectively eliminates biological threats like bacteria and viruses, it drastically worsens the concentration of chemical contaminants already present in the water. The heat required to address microbiological contamination accelerates chemical reactions that make the water significantly more toxic and dangerous to consume.
The Effectiveness of Boiling Water
Boiling water is a widely recognized and simple method of thermal disinfection highly effective against waterborne pathogens. Heating water to a high temperature, specifically a rolling boil, is sufficient to inactivate microbes that cause disease. The process kills bacteria like E. coli and Salmonella, and viruses such as Hepatitis A.
Boiling is also one of the most reliable ways to eliminate protozoan cysts, including Giardia and Cryptosporidium, which are resistant to chemical disinfectants like chlorine. Thermal inactivation occurs rapidly, with pathogens destroyed in less than one minute once the water reaches boiling point. For safety, the standard recommendation is to maintain a rolling boil for at least one minute to ensure complete disinfection, especially at lower altitudes.
Chemical Components Found in Pool Water
A standard swimming pool contains a complex mixture of chemicals designed to maintain sanitation and water balance, which are not removed by boiling. The primary component is a disinfectant, typically chlorine or bromine, used to kill microorganisms and prevent illness. These sanitizers react with organic matter like sweat, urine, and cosmetics to form combined chlorine compounds known as chloramines.
Pool water often contains cyanuric acid (CYA), which acts as a stabilizer for chlorine, preventing its breakdown by sunlight. Other common additions include pH adjusters (inorganic salts) and algaecides, which can introduce heavy metals like copper. These chemical components are necessary for pool maintenance but represent a significant contamination risk if the water is consumed.
Why Boiling Increases Chemical Toxicity
Boiling pool water poses a serious health risk because the process concentrates non-volatile chemicals and generates toxic byproducts. As the water boils, pure water vaporizes as steam, but non-volatile substances like salts, heavy metals, and cyanuric acid remain behind. This evaporation drastically increases the concentration of these dissolved solids, making the water more dangerous to drink than before it was heated.
Heating chlorinated water accelerates the formation of harmful disinfection byproducts (DBPs). High temperatures cause the residual chlorine to react with organic matter, forming compounds such as Trihalomethanes (THMs) and Haloacetic Acids (HAAs). These DBPs are linked to long-term health concerns, and their production is proportional to the water temperature and the concentration of organic matter.
An immediate danger is the inhalation of toxic vapors released during the boiling process. Heating volatile compounds like chlorine and certain DBPs causes them to off-gas into the air. Inhaling these concentrated fumes, especially in an enclosed space, can cause severe respiratory irritation and potentially lead to a health emergency.
Emergency Alternatives for Drinking Water
Since boiling pool water is unsafe, individuals needing emergency drinking water should seek alternative sources and purification methods. One highly effective approach is solar distillation, which involves boiling water and then condensing the pure steam back into a separate container, leaving all non-volatile chemical contaminants and pathogens behind. A simpler method, solar water disinfection (SODIS), uses clear plastic bottles filled with water placed horizontally in direct sunlight for several hours to allow the sun’s ultraviolet rays to kill pathogens.
For emergency disinfection, clean, unscented household chlorine bleach (sodium hypochlorite) can be used to treat water if boiling is not possible. The recommended dosage is typically eight drops of 6% bleach per gallon of water, followed by a 30-minute waiting period. Commercially available water purification tablets, often containing iodine or chlorine dioxide, are a convenient and reliable way to kill waterborne germs.