What is the primary purpose of Sodium Fluoride and Hydrofluosilicic acid in water treatment?

Sodium fluoride and hydrofluosilicic acid are both used primarily for the fluoridation of drinking water. The addition of these compounds to water supplies helps in the prevention of dental caries (tooth decay) by promoting the remineralization of tooth enamel. This public health measure is based on extensive research demonstrating the benefits of fluoride in reducing cavities, particularly in community water systems where the population can greatly benefit from consistent exposure to optimal levels of fluoride.

The purpose of these chemicals is not to purify the water or remove contaminants, although they can be part of broader water treatment processes. Purification typically involves processes that remove pathogens and other impurities, while fluoride specifically targets dental health. Similarly, while balancing pH levels in water treatment is important for various operational reasons, fluoridation does not serve this function; that role would typically involve other chemical additives designed specifically for pH adjustment. Thus, the primary purpose of these substances is indeed fluoridation, making the chosen answer the most accurate in this context.