What causes water hardness in water supplies?

Water hardness primarily results from the presence of dissolved calcium and magnesium salts in water supplies. These minerals can come from various sources, including limestone and gypsum, which are commonly found in the environment. When rainwater or surface water percolates through these geological formations, it can dissolve the calcium and magnesium, ultimately leading to higher concentrations of these minerals in the water.

Hard water can lead to various issues, such as scale buildup in plumbing and water heating systems, making it less efficient. This build-up is primarily due to the precipitation of calcium and magnesium compounds when water is heated or subjected to evaporation. Understanding the properties of hard water is essential for water treatment processes, where operators often need to implement methods to soften the water, especially in areas where water hardness can impact appliances and overall water quality.

Other options do not result in water hardness. For example, iron and copper can cause staining and other water quality issues but are not primary contributors to hardness. Sodium and potassium are associated with water softness. Bicarbonates and sulfates are often present in water but do not contribute to hardness in the same way calcium and magnesium do.