Bicarbonate (HCO3-) is an alkaline compound naturally present in water from rock dissolution. It affects water hardness and pH but is not typically harmful to health.

Bicarbonate (HCO3-) forms when carbon dioxide dissolves in water and reacts with minerals. It's a key component of the carbonate system that regulates water's pH. Bicarbonate levels are measured through titration or ion chromatography. While it contributes to water hardness, bicarbonate acts as a natural buffer, helping to stabilize pH levels in water bodies. It enters drinking water sources through the weathering of limestone and other carbonate rocks. High levels may affect taste but are generally not considered a health concern in drinking water.