What chemical is commonly used to raise pH in water?

Lime is commonly used to raise pH in water because it efficiently increases alkalinity and neutralizes acidity. It is a strong base, and when added to water, it reacts with the hydrogen ions (H⁺) present, resulting in an increase in pH. This process is particularly important in water treatment as it helps to prevent corrosion in pipes and equipment, encourages the precipitation of metals, and aids in the removal of certain contaminants, thereby improving water quality.

Soda ash is also a base and can be used to raise pH, but lime is more commonly utilized due to its effectiveness and dual role as both a pH adjuster and a source of calcium, which can be beneficial in certain water treatment processes. Alum, on the other hand, is primarily a coagulant and is not used for pH adjustment. Chlorine is a disinfectant and does not have any effect on pH levels directly. Hence, lime stands out as the optimal choice for effectively raising pH in drinking water treatment processes.