We have a Zero water purifier and it is awesome! We’ve got hard water so the filters have to be replaced quite often. But I tore into one and it’s a layer of charcoal and a layer of sand. I’m going to try to make one.
We have a Berkey and thinking of getting another one. Also making a rocket stove out of #10 cans.
Has to be more then just sand. My guess would be DI resin ? Or maybe some type of crushed Zeolite ? Been running an RODI filter on some Texas tap water. Out of the tap it is 450-500 ppm. My RODI (reverse osmosis and deionization unit) filter it down to about 1 ppm. When you buy filtered water from stores around here, that is filtered as you get it, the ppm is still around 90. It is safe to drink though.