What contributes to temporary hardness in water?

Temporary hardness in water is primarily caused by the presence of calcium and magnesium ions, which can form soluble bicarbonates. When water with these bicarbonate salts is heated or subjected to evaporation, the bicarbonates decompose, leading to precipitate formation as calcium carbonate and magnesium carbonate. This process indicates a direct link between these ions and the concept of temporary hardness, as the hardness can be removed through processes such as boiling.

In contrast, other factors such as high phosphorus content, excessive iron levels, or low pH levels are related to other water quality issues but do not directly contribute to the temporary hardness classification. Phosphorus can lead to nutrient pollution, iron can affect color and taste, and low pH can indicate acidity but none specifically cause the characteristic temporary hardness associated with the presence of dissolved calcium and magnesium bicarbonates.