“The aim of this study was to collect data on the fluoride concentrations in drinking water in the different regions of Switzerland.... In nearly sixty localities, fluoride content was equal or above 0.5 mg/l: for 24 wells, the fluoride concentration was between 0.5 mg/l and 0.7 mg/l; for another 35 wells, fluoride content was > or = 0.7 mg/l.” (Vivien-Castioni & Baehni, 2003)

Vivien-Castioni N, Baehni P - “Fluoride content of Swiss drinking water”  Schweiz Monatsschr Zahnmed 113(12):1276-80 (2003)
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Ret rieve&db=pubmed&dopt=Abstract&list_uids=14968702