Questioning the safety of swimming in water with high alkalinity is common, as water chemistry can seem complicated and technical. The overall safety of a swimming environment relies heavily on maintaining a precise chemical balance. High alkalinity is not a direct danger, but it creates conditions that are decidedly unsafe and uncomfortable for swimmers. This imbalance makes the water hostile to the human body and severely reduces the water’s ability to remain clean and sanitized.
Defining Alkalinity and pH Balance
Total alkalinity (TA) and pH are related but distinct measurements of water chemistry. The pH level is a measure of the water’s acidity or basicity, with a range of 0 to 14, where anything above 7.0 is considered basic or alkaline. Alkalinity, measured in parts per million (ppm), quantifies the concentration of alkaline substances, primarily carbonates and bicarbonates, that give the water its capacity to neutralize acids.
Alkalinity functions as a buffer, preventing the pH from fluctuating due to external factors like rain or chemical treatments. When alkalinity is too low, the pH becomes unstable and can swing erratically. When alkalinity is high, it locks the pH in place and often drives the pH upward, making it very difficult to lower. This resulting high pH is the central problem, causing immediate discomfort and safety issues.
Immediate Physical Effects on Swimmers
Swimming in water with high alkalinity and the resulting high pH can cause immediate, uncomfortable reactions in the body. The optimal pH for swimmer comfort is between 7.4 and 7.6, which closely matches the natural pH of human eyes and mucous membranes. When water pH rises above this range, the water begins to disrupt the body’s natural balance.
Swimmers often experience skin and eye irritation. The eyes may become red, itchy, and burn because the highly alkaline water is caustic to the sensitive tissues. For the skin, high pH strips away natural protective oils, leading to dryness, itching, and potential rashes. Mucous membranes in the nose and throat can also become irritated.
How High Alkalinity Impacts Water Quality and Sanitation
High alkalinity creates indirect safety hazards by compromising the water’s cleanliness and clarity. The most serious consequence is that elevated pH drastically reduces the effectiveness of chlorine and other sanitizers. For example, at a pH of 8.0, chlorine’s disinfecting power can drop to as low as 25% of its potential, leaving the water vulnerable to bacteria, viruses, and other pathogens.
High alkalinity also causes minerals to precipitate out of the solution, leading to cloudy water and the formation of scale. Cloudy water is a significant safety concern as it impairs visibility, increasing the risk of accidents. Scale, often appearing as chalky white deposits, builds up on pool surfaces and equipment, potentially clogging filters and reducing circulation efficiency.
Safe Swimming Parameters and Correction Methods
To ensure a safe and comfortable swimming environment, water chemistry must be maintained within specific ranges. The recommended range for Total Alkalinity is between 80 and 120 parts per million (ppm). The ideal pH range for treated water is 7.4 to 7.6.
When total alkalinity is too high, a strong acid is introduced to neutralize the excess alkaline substances. Chemical products like muriatic acid (hydrochloric acid) or sodium bisulfate are commonly used. The acid converts the alkaline ions into carbon dioxide, which is then released from the water, effectively lowering the alkalinity. To prevent damage, these adjustments are often done gradually, sometimes lowering the alkalinity by no more than 10 to 20 ppm per day.