How effective are phosphates at controlling color?
Color in a water system may be the result in the precipitation of soluble iron/manganese when they react with dissolved oxygen, chlorine disinfectant, and other oxidizing agents during water treatment. Polyphosphates bind-up the Fe/Mn, keeping them in solution and preventing the color from initially forming. Another source of color is the natural release of soluble iron by-products that appear to be ‘bleeding’ from the scale deposits (tuberculation) inside water pipes. Polyphosphates bind with soluble iron before it turns color (precipitates), while orthophosphates react with the pipe surface to slow down pipe corrosion and the release of corrosion particulates. Blended mixtures of ortho/ polyphosphates control both sources of potential color at the water supply and in the distribution system.
