What salts can cause hardness of water?

The primary salts responsible for water hardness are calcium (Ca²+) and magnesium (Mg²+) salts. These ions can react with anions such as carbonate (CO3²⁻), bicarbonate (HCO3⁻), sulfate (SO4²⁻), and chloride (Cl⁻) to form various minerals that contribute to water hardness. Here are some common water-hardening salts:

Calcium carbonate (CaCO3): This is the most common cause of water hardness and is often referred to as "lime scale." It forms when calcium ions react with carbonate or bicarbonate ions.

Magnesium carbonate (MgCO3): Similar to calcium carbonate, magnesium carbonate also contributes to water hardness and can form scale deposits.

Calcium sulfate (CaSO4): This is commonly known as "gypsum" and is found in certain geological formations. It can dissolve in water and contribute to hardness, especially in areas with high sulfate concentrations.

Magnesium sulfate (MgSO4): Also referred to as "Epsom salt," magnesium sulfate can cause water hardness and can have a laxative effect when consumed in high amounts.

The presence and concentrations of these salts in water determine the degree of water hardness. Hard water can have various drawbacks, including reduced soap and detergent effectiveness, scale buildup in plumbing systems, and an unpleasant taste or smell. In contrast, soft water is generally considered more desirable for household and industrial purposes.