The water test analysis and interpretation will provide information about both naturally-occurring substances and those resulting from human activity. Treatment of contaminated water supplies should be considered only as a temporary solution. How reverse osmosis works Reverse osmosis is sometimes referred to as ultrafiltration because it involves the movement of water through a membrane as shown in Figure 1. The membrane has microscopic openings that allow water molecules, but not larger compounds, to pass through. Some RO membranes also have an electrical charge that helps in rejecting some chemicals at the membrane surface.
Proper maintenance is essential to retain effectiveness over time.
Some units are equipped with automatic membrane flushing systems to clean the membrane. The effectiveness of RO units is characterized by the rejection rate or rejection percentage. The rejection rate is the percent of a contaminant that does not move through, or is rejected by, the membrane. Some typical rejection rates for common contaminants are shown in Table 1. These rejection rates are for single contaminants under design conditions.