For what purpose is lime added during water treatment?

Lime is added during water treatment primarily to raise pH levels and soften water. The addition of lime, which is calcium hydroxide (Ca(OH)2), increases the alkalinity of the water by neutralizing acidity. This adjustment is essential for improving the effectiveness of disinfection processes and for helping to stabilize the water.

Moreover, lime plays a significant role in the softening of water. It reacts with hardness ions, such as calcium and magnesium, forming insoluble compounds that can be removed through sedimentation or filtration. This process reduces scale formation in pipes and equipment, ultimately contributing to better operational efficiency in water distribution systems.

In contrast, coloring the water is not a function of lime; that would typically be a consequence of organic matter or other contaminants. Increasing water temperature is not a purpose of lime addition; temperature control usually involves separate mechanisms such as heating or solar exposure. While lime may indirectly affect taste by influencing pH, its primary purposes remain focused on pH adjustment and water softening.