When choosing a water filter, for most of us it always comes down to getting out the fluoride, and there are very few options.
So Mercola's would be out for me, and the Berkey system only removes fluoride with the addition of a $55 cartridge (pf-2) which contains 'activated alumina' (aluminum oxide) to adsorb fluoride and arsenic.
Activated alumina concerns me...although constantly we read it's safe, and only adsorbs the fluoride & arensic from water (it is not soluble in water); we know to avoid aluminum (in deodorants, baking powder, cookware, cans, etc). So running our water over/through it is safe? Fluoride can't get past the blood/brain barrier, but when it bonds with aluminum it can. So does the small amount of fluoride that gets past the activated alumina filter media then bond with the aluminum in the water? They say "no" because the aluminum oxide isn't soluble in water...
But is this something we can trust (as in "bet our health on")? Or something that 30 years from now will be found to be false? I don't know. I know that I chose an RO filter, and I recommend using distillation (with an activated charcoal post-filter) or reverse osmosis (with an activated charcoal pre-filter). And I also suggest that folks re-energize their filtered water with something natural (like sprouting seeds, grains of rice, or live plant/grass clippings, etc), if they discern they should.
Also remember, when looking at the "percentage of fluoride removed" with the activated alumina filters, be *sure* to note the 'flow rate'. If the water stays in contact with the activated alumina long enough, very high percentages of fluoride are removed. But if the water flows over/through the filter faster than it did in the testing lab, the 'percentage removed' will be MUCH less.
I think THE most insidious crime against us is that they've poisoned our planet to the point we cannot obtain pure, natural water. "Someday" :::sigh::: when we have the money & time to build a solar greenhouse, one of the things we're going to create is some kind of a 'small pond fountain' (that we fill with RO water) that will hold say 50 gallons...and the water will be misted & pumped up & over plants and trickle down to a small 'bentonite pond'. Every time I think of it I can hear my body saying, "Please hurry! That will be WONDERFUL!". And I agree, it will be wonderful (it just angers me that anyone would *have* to do something like that for naturally clean/energized water).
:::thinking out loud::: that is something that could done on a much smaller scale in virtually any home or apartment. In fact, if someone would make a **natural** 'water energizing fountain' (just add your own dirt, plants & 'whatever') and start selling them, they'd probably be overwhelmed with orders from the get-go.