Calcium chloride is a compound found in various water sources, sometimes naturally occurring and sometimes added intentionally. Understanding its characteristics and how it interacts with water helps clarify its presence in drinking water.
What is Calcium Chloride
Calcium chloride (CaClâ‚‚) is an inorganic compound consisting of calcium and chlorine atoms. It is a salt that appears as a white, crystalline solid at room temperature. Calcium chloride is highly soluble, readily dissolving in water and separating into calcium ions and chloride ions. This compound is odorless, has a distinctive salty taste, and is hygroscopic, meaning it attracts and retains moisture from the air.
How Calcium Chloride Enters Water
Calcium chloride enters water through natural geological processes and human activities. Naturally, it forms when ancient saltwater evaporates, leaving mineral deposits. Groundwater also picks up calcium from calcium-rich stones as precipitation seeps through the ground, forming hydrogen carbonate which can then release calcium ions. Volcanic gases and geothermal flows may also contribute to its presence in some natural sources.
Human activities significantly contribute to calcium chloride in water supplies. A major source is runoff from de-icing salts used on roads and sidewalks during winter. Industrial discharges and agricultural runoff also introduce this compound into water bodies. Chloride salts, including calcium chloride, can mobilize heavy metals from sediment into water, potentially affecting water quality.
Intentional Uses of Calcium Chloride in Water
Calcium chloride is intentionally added to water for several purposes. In municipal water treatment, it helps regulate water hardness, preventing corrosion in pipes and equipment by balancing water chemistry. It also enhances coagulation and flocculation processes, where it helps suspended particles clump together for easier removal, improving water clarity. It can assist in removing contaminants like heavy metals and phosphates through precipitation.
Bottled water companies add calcium chloride to purified water to enhance its flavor, as pure water can taste “flat.” In sports drinks, it functions as an electrolyte, helping to replenish minerals lost during physical activity. Calcium chloride is also used in food processing, such as in pickling or cheesemaking, where it might end up in wash water or as an ingredient. It acts as a firming agent for vegetables and fruits, maintaining their texture.
Effects of Calcium Chloride in Drinking Water
The presence of calcium chloride in drinking water can influence its taste and contribute to water hardness. Water with elevated chloride levels, including from calcium chloride, can have a salty taste, especially at concentrations above 250 mg/L. It also contributes to water hardness, as it adds calcium ions to the water. Higher hardness can lead to scale buildup in pipes and appliances over time.
From a health perspective, calcium chloride in typical drinking water concentrations is generally considered safe. Calcium and chloride are essential electrolytes in the human body. However, consuming water with very high concentrations of calcium chloride can lead to gastrointestinal issues, such as stomach cramps, nausea, or diarrhea. While adverse effects are usually associated with very high doses uncommon in drinking water, industrial-grade calcium chloride is not intended for consumption and may contain impurities.