It is protected by the preceding reverse osmosis membrane which in turn is protected by the carbon block filter which is preceded by the sediment filter. If any one of these critical components is not properly selected or is of sub-standard quality premature failure of downstream components can result. Sediment Filters First, let's talk about sediment pre-filters and the difference between absolute and nominal micron ratings. In an absolute rated filter all particles larger than the stated micron rating are removed by the filter. In a nominal rated filter a certain percentage of particles larger than the nominal rating will actually pass through the filter.
Most sediment filters are of the nominal rating variety.
New micro-sediment filters are absolute filters and provide superior protection of downstream carbon filters and membranes. Next in line are carbon block filters. The primary function of these filters is to remove chlorine and further filter out sediment. Since carbon block filters are absolute filters and are prone to plugging with sediment it is essential that they are preceded by a very high efficiency sediment filter. The best means of determining when to replace the filter is to test the waste water stream for presence of chlorine.