Which chemical is typically added to prevent corrosion in water distribution systems?

The addition of orthophosphate in water distribution systems is primarily aimed at preventing corrosion in pipes and other components of the water supply infrastructure. Orthophosphate acts by forming a protective layer on the interior surfaces of pipes, thereby reducing the leaching of metals such as lead, copper, and iron into the water supply. This is especially important for aged systems where corrosion can significantly impact water quality and safety.

While chlorine is commonly used for disinfection purposes, it does not address corrosion directly and can even contribute to the deterioration of certain pipe materials. Fluoride is typically added to promote dental health but does not have a role in corrosion inhibition. Sodium hydroxide is used to adjust the pH levels of water but does not specifically aim to prevent corrosion as effectively as orthophosphate. Thus, orthophosphate stands out as the preferred choice for controlling corrosion in water distribution systems.