 Typical Rejection Characteristics of Thin Film Composite (TFC) Reverse Osmosis Membranes
Below are the typical rejection (removal) percentages of a standard thin film (TFC) reverse osmosis membrane. These are averages based on experience and are generally accepted within the industry. They are not a guarantee of performance. Actual rejection can vary according to the chemistry of the water, temperature, pressure, pH and other factors.
We should point out that the listing below is of items that are treated by the RO membrane alone. Home RO units, which consist of carbon filters as well as a membrane, can remove innumerable chemical contaminants that are not listed on this chart. Here’s an article that explains what carbon filtration adds to the total removal capability of home RO units.
Estimated Reverse Osmosis Rejection Percentages
The reverse osmosis process uses a semi-permeable membrane to reject a wide variety of impurities. Here is a partial list.
| Aluminum | 97-98% | Nickel | 97-99% | |
| Ammonium | 85-95% | Nitrate | 93-96% | |
| Arsenic | 94-96% | Phosphate | 99+% | |
| Bacteria | 99+% | Polyphosphate | 98-99% | |
| Bicarbonate | 95-96% | Potassium | 92% | |
| Boron | 50-70% | Pyrogen | 99+% | |
| Bromide | 93-96% | Radioactivity | 95-98% | |
| Cadmium | 96-98% | Radium | 97% | |
| Calcium | 96-98% | Selenium | 97% | |
| Chloride | 94-95% | Silica | 85-90% | |
| Chromate | 90-98% | Silicate | 95-97% | |
| Chromium | 96-98% | Silver | 95-97% | |
| Copper | 97-99% | Sodium | 92-98% | |
| Cyanide | 90-95% | Sulphate | 99+% | |
| Ferrocyanide | 98-99% | Sulphite | 96-98% | |
| Fluoride | 94-96% | Zinc | 98-99% | |
| Iron | 98-99% | |||
| Lead | 96-98% | Insecticides | 97% | |
| Magnesium | 96-98% | Detergents | 97% | |
| Manganese | 96-98% | Herbicides | 97% | |
| Mercury | 96-98% | Virus | 99+% | |
| TDS (Total Dissolved Solids) | 95-99% | Hardness | 93-97% | |
