Oh, I forgot to mention.. That does not mean your RO is 10 ppm.. It really depends on how your water coming in is.. I notice that when the ppm increases in my tap water, my RO water also increases.. So if we look at proportionate numbers, if your tap is lets say 600 ppm, its possible your RO will be 20 ppm or higher.. etc

I actually test my water monthly.. fill 3 glasses, 1 RO, 1 Distilled, and 1 Tap.. Clear the instrument by measuring the distilled (0).. Measure the RO, clear again in the distilled (0), measure in Tap, then clean in distilled. I then take 1-(RO ppm / TAP ppm) and get a percentage of effectiveness.. I get around 96-97% most of the time