If the alkalinity is equal to or greater than the total hardness, what type of hardness is present?

When alkalinity is equal to or greater than total hardness, the water in question typically exhibits characteristics of temporary hardness. Temporary hardness is primarily caused by the presence of bicarbonate and carbonate ions, which can be removed by boiling the water. The presence of bicarbonate alkalinity indicates that there are readily soluble compounds that can decompose upon heating, which means they can be precipitated out of the solution, thus lowering hardness.

In contrast, permanent hardness is generally associated with sulfate and chloride ions, which do not change upon boiling and are hence not removed through this process. Mixed hardness refers to water that contains both temporary and permanent hardness components, but specifically, when alkalinity meets or exceeds total hardness, it typically signifies the predominance of temporary hardness.

Understanding the relationship between alkalinity and hardness is crucial in water quality management, especially for ensuring that water treatment processes are appropriately designed to address the specific type of hardness present.