What does a reverse osmosis filter do?
A reverse osmosis filter is a fine grained small pore filter that is used in water filtration.  The RO filter membrane reduces 99.9% of 1000+ contaminants down to 0.0001 microns.  Some of the contaminants it removes are chlorine, lead, heavy metals, fluoride, volatile organic compounds (VOCs), chloramine, total dissolved solids (TDS), limescale, and arsenic.  A reverse osmosis membrane is a great way to make clean water at home if you are trying to get rid of bottled water consumption.