Reverse Osmosis (RO) is a water purification process in which water is forced through a semi-permeable membrane that removes 92-97% of tap water impurities. The result is water that is free of minerals and other contaminants. There are filters incorporated before and after the membrane to both protect the membrane and to polish the water on the way to the dedicated faucet. Since this is a slow process and not just a flow through filter, there is a small storage tank that captures and distributes the water as needed.

What does RO remove?
Rejection Characteristics Of Reverse Osmosis Membranes:
Sodium 85 - 94%
Sulfate 96 - 98%
Calcium 94 - 98%
Potassium 85 - 95%
Nitrate 60 – 75%
Iron 94 – 98%
Zinc 95 – 98%
Mercury 95 – 98%
Selenium 94 – 96%
Phosphate 96 – 98%
Lead 95 – 98%
Arsenic 92 – 96% *
Magnesium 94 – 98%
Nickel 96 – 98%
Fluoride 85 - 92%
Manganese 94 – 98%
Cadmium 95 – 98%
Barium 95 – 98%
Cyanide 84 – 92%
Chloride 85 – 92%
Pharmaceuticals 99.9%
Hormones 99.9%

The removal percentage will vary based on membrane type, water pressure, water temperature and total dissolved solids.
Activated carbon filtration that accompanies a reverse osmosis system will also remove below:
Chlorine 99.9%
VOCs (volatile organic compounds) 99.9%
Trihalomethanes (byproducts of chlorination) 99.9%

*Results not guaranteed based on various water conditions.