Certain areas of Chennai, India, are supplied with water with very high fluorine content. The community cannot use RO-based treatment (reverse osmosis) due to cost considerations. We would prefer to use some chemicals to inactivate fluorine or to filter it. Any suggestions on how this could be dealt with? Please suggest which treatment is best at household level and which in the utility. I could provide test reports, if necessary, for a non-RO based solution.