Steve_D wrote:I didn't know that any reverse osmosis system could give a reading as low as 1 TDS!
Hah, I didn't either. I had it for a full year in Boulder without replacing any of the filters. Initially when I set it up, it was giving me a TDS reading of 11ppm. By the time we moved here to Ashland, it was up near 50ppm and tap water in Boulder was 75ppm or so.
So, when we made the move, I put new filters in it. The TDS measurement didn't drop though! So I had to change the main membrane, which was $40. Basically now it's like a brand new unit.
Steve_D wrote:Do you know what brand of RO unit you have, and how old it is?
I have a Watts Premier's WP-4V. It was on sale at CostCo about 2 years ago (March 2008) when I bought it.
I'll probably not change the main membrane filter again until the TDS measurement gets up near 30ppm. You're supposed to change the other filters every 6 months, but if the TDS measurement is below 10, I'll probably not mess with them.