Aren't you saying the same thing as Ziggy? your RO/DI unit is working, but not up to it's full capacity. A Rose by anyother name is still a rose..I disagree with ziggy. I have a 75 gpd unit with a pressure gauge and a dual tds meter. My water pressure is normally around 30 psi and it still produces 0 tds. It just takes longer to make water.