Just bought a TDS meter, along with some new filter blocks and DI resin for my RO/DI. I haven't changed any of the filters on the RO/DI in about a year and a half now......I know, shame on me. So I was curious to see what the TDS is coming out of the unit. Turns out, its 2. I have 280 out of the faucet. What is normal for San Antonio? Now I'm debating on whether to change out the filters. The resin is shot, the color is orange, but apparently all the tds is still being removed. Would you cange out the filters? Or hold on to them until necessary.