Water in this condition has the tendency to deposit calcium carbonate on the insides of pipes in the distribution system and in the plumbing of your house. Carbon dioxide gas is bubbled through the softened water to lower the pH to a level at which the water is stable. Poly phosphates are also added to the water to help maintain stability. Filtration Just before leaving the treatment plant, the water passes through filter beds composed of sand and anthracite 36 inches deep. The filters trap any floc which did not settle out in the clarifiers, and remove small, suspended particles, making the water sparkling clear.
Ammonia is combined with the chlorine to form chloramine.
These chloramines retain their disinfection property longer than pure chlorine and also prevent the water from developing a chlorine taste. The disinfection process receives careful control to insure that the concentration of chlorine is high enough to destroy bacteria but low enough that the taste of the water does not change. The disinfectant is added after the water has been filtered.