How about using membrane ...
Published by Paul Jacob, Asian Institute of Technology (AIT) - Research Associate
How about using membrane distillation. As fluoride is non volatile MD will not let the water quality drop due to this. But it depends on the raw water quality also eg. TSS, TDS etc. This technology is relatively new. But rest assured you will have very high quality water with no TDS, no metals ions etc. But if you have volatile like ammonia it will pass. No chemical precipitation required. Also the system does not use pressure, it works at a fraction of the cost of RO or NF. Research have been done and validated the process. You can look it up online for additional details. I just wanted to bring MD into the picture as I didnt see anyone talking about it. Cheers, Paul