RESUMOFluoretação da água de abastecimento público é a adição de compostos de flúor nas estações de tratamento da água como uma das formas de prevenção da cárie dentária. Este estudo avaliou a situação da fluoretação das águas de abastecimento no município de Lages, Santa Catarina, sistematizando dados de 10 anos de heterocontrole (2004-2013 ). Recomenda-se a adoção de medidas efetivas para garantir à população o consumo de água tratada com qualidade, o que inclui teores adequados de flúor na água e manutenção de ações de vigilância sanitária por parte das autoridades de Saúde Pública. PALAVRAS-CHAVE:Fluoretação da Água; Tratamento da Água; Controle da Qualidade da Água; Análise da Água; Abastecimento de Água; Monitoramento da Água; Vigilância Sanitária ABSTRACTThe public water supply fluoridation is the addition of fluorine in the water treatment plants, as a way of preventing tooth decay. This study evaluated the situation of fluoridation of public water supply in the city of Lages, of the State of Santa Catarina, systematizing data from 10 years of external control (2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013). Monthly, every other day, 67 water samples from 11 points of supply were collected, totaling 737 samples. To determine the fluoride concentration in the water samples, an electrometric method was used. After analysis, the samples were classified according to the criteria of Ordinance nº 635/Bsd of 26/12/1975 (adequate or inadequate) and the criteria proposed by the Ministry of Health Collaborating Centre for Surveillance of Oral Health (CECOL) of the University of São Paulo (benefits and health risks of the population). Of the samples analyzed, 58.6% had adequate levels of fluoride and 51.1% had maximum benefit and low risk, according to each criterion. Of the inadequate samples of fluoride concentration, 34.7% stood at levels above 1.0 mg L -1 and 6.7% at low levels of fluoride in water (<0.7 mg L ). It is recommended to adopt effective measures to ensure that the population ingests treated water quality, including appropriate levels of fluoride in the water and the maintenance of health surveillance by the Public Health authorities.