It’s a long read from my water source treatment plant but it would appear they use chlorine.
Treatment Process
Conventional water treatment is used at both the R.B. Simms and Whitlock treatment plants. "Raw"water from the reservoir is first passed through a screen to remove large objects, and then treated with chlorine. The chlorine aids in removal of iron and manganese, two natural substances in the water which would stain clothing and plumbing fixtures if not removed. The chlorine also acts as a disinfectant, destroying bacteria, viruses, algae, and other organisms, some of which could cause illness. Alum, lime, and polymer are then added. In a process called coagulation, these substances combine with each other and with fine particles in the water to form a substance called "floc" which is heavier than water. Powdered activated carbon is added at this stage as needed to help remove unpleasant tastes or odors. The water then passes through large basins where the floc settles to the bottom and is removed, taking unwanted substances with it. Clear "settled" water is skimmed from the top of the basins and filtered to remove still more unwanted material. Additional chlorine disinfectant and lime are added as needed to meet state requirements. A corrosion inhibitor containing zinc and phosphate is added to preserve distribution piping and prevent lead and copper contamination. Finally, fluoride is added to prevent tooth decay.
