I had my doubts that the filter would actually result in in a TDS of 0ppm.  So i ran an analysis of the ZeroFiltered water in my lab according to Standard Method 2540 C.  I was shocked to see that I got an actual 0ppm (equivalent to 0 mg per Liter of water). Even my "Blank" source of Deionized water was higher than the Zerowater filtered water!  I'm a believer now!  I love the large capacity of the 30 cup dispenser that still fits nicely in my refrigerator.  My favorite part is that the reservoir on top  holds more than 1/2 gallon of water so that I can fill that up and let it do its magic!