... L), or in parts per million(ppm).The lower TDS level in the water, the more efficiently your body’ ... (1grain=17ppm)*Make sure you always drink pure water!FEATURESHold function: Saves measurements for convenient reading and ... measures from 0-999ppm, with a resolution is 10 ppm, indicated by drinking*10 image, factory calibrated.Range:0 ... . If you are testing higher p (member, water quality association)