The science of filtration has progressed exponentially in the last one-hundred years. We can now filter sea water with synthetic membranes by reverse osmosis to remove ions of sodium and chloride to make drinking water. We have available for our use nano-filtration, ultra-filtration and micro-filtration using manmade fabrics, membranes and hollow fibers. Electrodialysis Reversal can use electrical current to remove dissolved solids including low-atomic number ions from water. Still the majority of filtration applications call for inexpensive gravity or pressure filtration through granular media. In fact, the sub-micron filter systems still need suspended solids removal ahead of them to avoid fouling of the membranes.