Alkalinity measures water's acid-neutralizing capacity, with CaCO3 as reference. It affects taste, pipe corrosion, and water treatment. Not a contaminant, but a key quality parameter.

Alkalinity occurs naturally in water due to dissolved minerals, primarily from limestone. It's been a crucial factor in water treatment since the 19th century. While not a contaminant, alkalinity significantly influences water quality and infrastructure. It determines how well water resists pH changes, which is vital for preventing pipe corrosion and optimizing water treatment processes. High alkalinity can lead to scale buildup, while low alkalinity may increase metal leaching from pipes.