Where do you hook up your inline TDS meter?

[mediaone]

Emily, seems like you got it sorted out but I will throw in my opinion just in case you find it helpful.

It doesn't matter if you install the unit (Tap Water - Post DI) or (Tap Water - Post RO) or (Post RO - Post DI). It simply allows you to see the difference between the two points. That being said, some people don't really care what their tap water is (especially locally) because our water is quite pure to begin with. Installing it (Tap Water - Post RO) will help you determine if you RO is pulling out a significant amount of TDS and may give you an indication over time of whether or not the membrane needs to be flushed or replaced. If all you care about is TDS at the end (usually our overall concern)... installing it (Post RO - Post DI) will allow you to keep an eye on the DI resin and overall quality at the end. Keep in mind that RO membranes are usually good for 3-5 years provided they are backflushed periodically.