What are the two main causes of hardness in water?

The two main causes of hardness in water are calcium and magnesium. Hardness is primarily a result of the presence of these two minerals in water, which typically comes from the natural dissolution of limestone, chalk, or gypsum in the soil and rocks through which the water flows. Calcium ions (Ca²⁺) and magnesium ions (Mg²⁺) can accumulate in water supplies and contribute to the formation of scale in pipes and appliances, which can lead to various issues in water systems, such as reduced efficiency in heating systems and increased maintenance costs.

Addressing these causes is essential for water treatment in a very small water system, as softening treatments may be required to reduce the hardness and prevent scaling. Understanding this key concept about water hardness is crucial for effective water system management.