Making pool water safe for drinking in a survival scenario requires a multi-step chemical and biological purification process, not simple filtration. It is not immediately potable due to the presence of chemicals added for sanitation and maintenance. This complex purification is only justifiable in a severe emergency when no other treated or natural water source is available. The process requires eliminating both high concentrations of sanitizers and biological contaminants.
How Pool Water Differs from Natural Sources
Pool water is chemically treated to prevent the growth of pathogens and algae, making its composition fundamentally different from a lake or stream. The most significant difference is the presence of high levels of chlorine, typically maintained between 1.0 and 3.0 parts per million (ppm) of free available chlorine. While municipal tap water is also chlorinated, pool levels are often higher and can be irritating or harmful if consumed directly over time.
A primary concern in outdoor pools is the chlorine stabilizer, cyanuric acid (CYA), which is added to prevent chlorine from being rapidly degraded by the sun’s ultraviolet rays. Pool CYA levels are usually kept between 30 and 50 ppm, a concentration that is not found in natural sources. Algaecides and flocculants are also introduced, which can contain toxic compounds like copper ions or other heavy metals. Non-biological contaminants such as sunscreen, body oils, and dissolved solids also contribute to the overall impurity of the water.
Neutralizing Chemical Additives
The first and most unique step in treating pool water is the neutralization of chlorine and cyanuric acid. Chlorine is a volatile chemical and is the easiest to remove through natural processes like aeration and solar exposure. Leaving the water uncovered and exposed to direct sunlight for 24 to 48 hours allows the ultraviolet radiation to break down the chlorine, causing it to off-gas or evaporate into the atmosphere.
For a quicker method, chemical neutralization can be achieved using a reducing agent such as sodium thiosulfate, a compound commonly available in pool supply kits or photography darkrooms. Sodium thiosulfate reacts almost instantly with chlorine, converting it into harmless chloride ions. However, this chemical approach only addresses the chlorine and does not remove other dissolved solids.
The most challenging chemical to eliminate is cyanuric acid because it is highly stable and does not evaporate or break down easily with simple boiling. High concentrations of CYA, which can exceed 100 ppm, are best removed by distillation, which physically separates the pure water vapor from non-volatile solids. Without distillation, the only other way to lower CYA is through dilution or using a reverse osmosis filter, neither of which is likely to be an option.
Eliminating Biological Contaminants
Once the chemical levels are significantly reduced, the water must be purified to eliminate any surviving biological contaminants. Despite the chemical treatment, pathogens like bacteria, viruses, and protozoa can still be present, especially if the CYA concentration has reduced the chlorine’s effectiveness.
Boiling is the most reliable emergency method for sanitization, as the high temperature is lethal to microorganisms. The water should be brought to a full, rolling boil for at least one minute at sea level to ensure the thermal inactivation of all pathogens. At altitudes above 6,500 feet, the boiling time should be extended to three minutes due to the lower boiling temperature of water in thinner air. Boiling does not remove chemical contaminants but effectively kills all waterborne disease-causing agents.
A superior, yet more complex, method that addresses both chemical and biological threats is distillation. This process involves boiling the water and collecting the resulting steam, which is pure water vapor. When the steam condenses back into liquid water, it leaves behind virtually all dissolved solids, heavy metals from algaecides, and non-volatile chemicals like cyanuric acid. A simple emergency distiller can be improvised by collecting the steam condensation, ensuring the resulting water is the purest possible.
Safety Warnings and Emergency Use Context
The process of making pool water drinkable is complex, and the potential for residual chemical contamination remains a serious risk. Ingesting high levels of copper-based algaecides can cause immediate symptoms such as vomiting, severe nausea, and potentially damage internal organs. While cyanuric acid itself has low immediate toxicity, consuming high concentrations can lead to gastrointestinal distress and irritation. This purification protocol should only be undertaken in a genuine survival situation where no other source of safe drinking water is available. The process is imperfect, and consuming the water carries the risk of illness if purification fails or if chemical levels remain dangerously high.