Spend any amount of time researching a clean drinking water solution for your home and you'll inevitably run into the term reverse osmosis (or RO for short). If you're a normal individual and not a scientist or a water engineer, the phrase should give you pause. Sure, you could google "Reverse Osmosis" and get temporarily lost in jargon, or you could read on and get a fuller understanding of the best system for your home's drinking water.
Reverse osmosis is simply the process by which the water is purified. Inorganic materials such as ions, molecules, particles, bacteria and other things that you really don't want to consume are flushed out through a semi-permeable membrane, leaving only pure, filtered drinking water. The membrane is filled with tiny pores that allow the hydrogen and oxygen molecules to pass through, as long as they aren't attached to anything else. In other words, while H2O is small enough to pass through the pores, C8H14ClN5 (Atrazine, an herbicide commonly found in tap water) isn't coming through because it's too big for the membrane's pore. C6H4(CH3)2 (Xylene, a solvent also found in your water) isn't making it out either. And there are many, many more.
The one thing you don't want to forget is this: H7O57 is too big to make it...that's E. coli.
How does the system work? There are three (and an optional fourth) components involved: A pre-filter, which takes in the tap water andfilters out heavy metals such as rust and mercury and large sediments like calcium carbonate, up to 5 microns.
The remaining fluid is shot through the membrane at high pressure. Constructed of several layers of polypropylene mesh, the membrane's tiny pores stop virtually all elements other than H2O, leaving purified water. The list of contaminants the RO sends to waste is quite long, but here's a sampling:
Then the water passes through the last carbon filter, called a post-filter, which filters out anything the other filters somehow missed. The purified water then goes into a 2.2 gallon (or an optional 3.2 gallon) tank, where it is stored until the spigot is activated.
The result is pure, clean, healthy water in your glass or pan.