Opinions on RO/DI systems

[Myka]

Depends what your tap water is like. My tap water has a tds of 92, and the water coming out of my RO is 1 ppm, so my DI cartridge doesn't have to work very hard at all.

I think each DI cartridge can only filter up to 40 ppm, so if your water after going through RO is higher than 40, then you'll need additional DI. I am not so sure I am correct on that though...