💧What is SDI? Silt Density Index (SDI) is a measure of the fouling potential of feed water, especially important for RO membrane protection. It estimates how much particulate matter (silt, colloids, bacteria, etc.) would clog a 0.45 µm filter over a standard time. The SDI was introduced by ASTM as a standard fouling index to address the growing need for a reliable … [Read more...]