Water fluoridation is the adjustment of the natural concentration of fluoride in drinking water to the optimal recommended level for the prevention of dental decay. The Health (Fluoridation of Water Supplies) Act 1960 and the Fluoridation of Water Supplies Regulations 2007 provide for the making of arrangements by the HSE for the fluoridation of public water supplies. The local authorities, acting on behalf of Irish Water, act as agents for the HSE in providing, installing and maintaining equipment for fluoridation and in adding the fluoride to water and testing the fluoride content of water to which fluoride has been added. Total expenditure on fluoridation in 2013 was €4.8 million. The costs include €1.7 million paid to Chemifloc Ltd for the supply and delivery of hydrofluorosilicic acid - the chemical used for fluoridating water, as well as operational costs of €2.1 million and capital costs of €1 million.