Page "Hard water" Paragraph 23

It is also worth noting that the LSI is temperature sensitive.

The LSI becomes more positive as the water temperature increases.

This has particular implications in situations where well water is used.

The temperature of the water when it first exits the well is often significantly lower than the temperature inside the building served by the well or at the laboratory where the LSI measurement is made.

This increase in temperature can cause scaling, especially in cases such as hot water heaters.

Conversely, systems that reduce water temperature will have less scaling.