Calgary water and RO; what's your TDS after the RO?

[Delphinus]

If you have an RO unit, and you measure your TDS, what typically is your TDS reading after RO membrane (but before the DI stage)?

I know incoming TDS is usually around 400 or so for me. But I was expecting my RO readings to be more in the 5-15 range after my RO, but I usually get readings more like 60-80.

I've replaced my membrane (and all the prefilters of course), but I still get readings like that. After the DI the readings are 0 so I think the TDS meter is OK.

Maybe something in my configuration is causing membranes to fail prematurely? Or can a RO unit be functioning properly and still yield water with a TDS in the 60 to 80 range?