A positive Langelier index may indicate what type of water?

A positive Langelier index indicates that the water has a tendency to deposit calcium carbonate, making it scale-forming. The Langelier Index (LI) is a measure of the equilibrium state of calcium carbonate in water and helps determine whether water is stable, corrosive, or scale-forming.

When the Langelier Index is above zero, it suggests that the water has higher levels of dissolved minerals compared to the saturation level of calcium carbonate, so the water will seek to reach equilibrium by depositing scale. This can have implications for plumbing systems, leading to build-up in pipes and fixtures. In contrast, a negative Langelier index indicates corrosive water, while a value near zero suggests that the water is neutral in terms of scale formation or corrosion potential. Thus, a positive value clearly indicates that the water is tending towards forming scale.