TDS meter reads 12

[jazonPartij]

I'm making RODI water, but my it still reads 12. Is that a low enough level or is something not right?

 

[saltyphish]

something is not right. You only want to use 0 tds water. How old is the filters/membrane on your unit? Maybe time to replace a few.

 

[TheEngineer]

This is RODI or just RO? What's your incoming TDS? @saltyfish is right, you are aiming for 0 tds.

 

[AZDesertRat]

If it is RO/DI you need three TDS readings to troubleshoot the system, tap water, RO only before the DI and final RO/DI. The age of the filters and membrane is less important that how efficiently the RO membrane and DI resin are working.
As mentione above, your goal is 0 TDS always since TDS is not a measurement of anything specific and you have no idea what that 12 TDS is made up of. It could also be operator error. What are you testing with and how? TDS meters must be kept squeaky clean as well as the container you capture and analyze the TDS sample in. You can easily carry over TDS from the tap or RO only water when sampling the final effluent and get bogus readings.

More information on your RO/DI system, its age, care and maintenance and your testing method would help.