Fluoride removal with extra low energy reverse osmosis membranes: three years of large scale field experience in Finland Original Research Article

Infiltration of surface water into the ground and a retention time of 50 days is a natural method to remove color, iron and manganese — which are typical for Nordic lake waters — and to produce a good quality drinking water. However, due to the geological situation in the Southern parts of Finland, the fluoride concentration increases after the soil passage from a typical value of 0.7 mg/L to values up to 1.8 mg/L. According to the drinking water directives of the European Union, the fluoride concentration shall be limited to 1.5 mg/L.