Water treatment facilities use a number of chemicals to purify, condition, and otherwise treat the water supply. The exact chemicals used will vary, depending on what needs to be achieved: for example, whether they're trying to disinfect, oxidize or control corrosiveness. Chlorine is the most common disinfectant and oxidant; several forms may be utilized. When water has an acid pH level, lime, sodium carbonate and zinc can treat corrosion problems. To fight algae growth on surface water, copper sulfate might be used. A chemical called potassium permanganate serves to reduce high iron content in water. When taste or odor is a problem, activated carbon may be part of the process. And in some areas, fluoride is added to the water supply, to reduce tooth decay. There are many other water treatment chemicals as well. Though most of these agents are filtered out by the treatment plant, some traces may remain in your tap water. The only way to know for sure is by testing it. To find out more about the chemicals in your water, contact the local water department, or a professional water conditioning company.