I understand that simple ...

I understand that simple treatment with alum at household level will reduce fluoride concentrations, not to the WHO level, but will make a difference depending on the pre-treatment concentration. At utility level, the use of activated alumina is a good option and can achieve WHO levels.  However if an alternative source can be found, that is optimum.  e.g. if households can collect rain water for their drinking water and use the high fluoride water for washing and cleaning, this can work if the community all adhere to this protocol.  Or the clinic can have a small activated alumina unit where villagers collect say 10 liters per day per household just for drinking and cooking, while using the high fluoride water for other purposes, it greatly reduces the cost as compared to treating all the water.