Langelier Saturation Index Calculator

The LSI is a calculated index used to predict the calcium carbonate stability of water. It indicates whether water will precipitate, dissolve, or be in equilibrium with calcium carbonate. The index helps determine if water is corrosive or scale-forming.

LSI values below 0 indicate corrosive water that may dissolve calcium carbonate from pipes and surfaces. Values above 0 suggest scale-forming water that may deposit calcium carbonate. Values near 0 (±0.3) indicate balanced water with minimal corrosive or scaling tendencies.

For swimming pools, an LSI between 0.0 and +0.3 is generally considered ideal. This range provides adequate protection against corrosion while minimizing scale formation on pool surfaces and equipment.

Temperature significantly impacts LSI calculations because calcium carbonate solubility decreases as temperature increases. Higher temperatures result in higher LSI values, making water more scale-forming. This is why hot water systems often have more scaling issues.

If LSI is too low (corrosive), consider increasing pH, alkalinity, or calcium hardness. If too high (scale-forming), reduce pH, lower alkalinity, or decrease calcium levels. Always make gradual adjustments and retest to achieve the desired balance.

Yes, LSI is commonly used to evaluate drinking water distribution systems. It helps water utilities prevent pipe corrosion and scale formation, ensuring water quality and extending infrastructure life. Balanced water protects both the distribution system and consumers' plumbing.

LSI calculation requires five key parameters: pH, water temperature, total dissolved solids (TDS), calcium hardness, and total alkalinity. All measurements should be taken from the same water sample under consistent conditions for accurate results.