What is the most effective corrosion inhibitor for controlling lead in a distribution system?

Orthophosphates are considered the most effective corrosion inhibitor for controlling lead in a water distribution system because they work by forming a protective layer on the interior surfaces of pipes. This barrier minimizes the leaching of lead and other metals into the drinking water. By stabilizing the corrosion process, orthophosphates can significantly reduce the solubility of lead compounds, thus lowering lead concentrations in the water supply.

Additionally, orthophosphates are generally more effective than other types of phosphates, such as polyphosphates, which may not provide the same level of protection and can sometimes lead to complex chemical interactions. While sodium silicate and calcium carbonate are also utilized in corrosion control, they do not specifically target lead as effectively as orthophosphates do. Sodium silicate primarily aids in silica-based protective coatings and may not address heavy metal leaching directly, whereas calcium carbonate mainly helps to increase water alkalinity but does not form a specific protective layer against lead.