Summary of TDS readings....

[inetmug]

I have looked at numerous TDS threads, but have not found my answer.

It is clear that TDS is only a measure of how good your RO/DI is doing, not water quality. I would suggest to everyone, especially in older homes, do a copper test on your base tap water (mine is zero). As a member pointed out, you can have low TDS, and bad things in the water. Knowing your starting point to understand what you need to setup is the key. 'Nuff said. Consider a home filtration as a starting point if you got really bad water. Better for you health, and cheap. then feed into your RO/DI.

My question stems around an acceptable range on a meter to indicate when it is time to change filters? I have heard anything up to 20 is acceptable out of the RO/DI unit. I am trying to validate this "claim".

I would think units with a guage, you take the pressure when all new, and then make a move at a certain delta off that base (just like a pool). Just like the TDS meter, same question, what would be the delta that would be acceptable? I was looking for specific on my unit, as this may change between manufacturer.

I have ATO water driven by a SpectraPure with gauge, and captive purity on the core SW maker setup (no gauge). Both are 3 stage with DI

[ReachTheSky]

Well, some folks would tell you that a TDS reading of even 1ppm means it's time to change it out and I tend to agree with this notion. If there are solids making their way through the membrane, then the membrane is exhausted.

But as you mentioned, the TDS is just a measurement of how much solids there are. What's more important is what those solids are and if they're harmful. A lot of expensive testing will reveal that to you if you're curious. As for me, I'd rather not chance that and just change it as soon as TDS goes above 0.