The tds from the tap is around 300ppm, and after the RO it is about 35ppm. I used the last of my resin this morning and the tds is back to zero after the DI vessel, but it is producing hardly any water to my storage tank, even though the water pressure is 45psi. I have ordered new filters yet again, and another bag of resin, hopefully better quality this time! I have had no end of trouble since changing from my ROman 450 to the Purefreedom 950, I don't know if it is the fault of the unit or the filters or resin? And Purefreedom have been no help whatsoever!