When fed with low TDS feed (e.g., feed purified by RO), the product can reach very high purity levels (e.g., 18 Megohms/cm[REF]).
One important aspect in the water treatment application is that some types of EDI needs to have feed water that is free from CO2, as well as other dissolved gasses, since these are in a dissolved form they will put unnecessary strain on the EDI unit and will reduce performance.