How much water will you need and do you know the pressure on supply.
If under 50lbs. you may need a pump.
Is your source chlorine or chloramine.
I am BRS for my RO/DI and regular water filters .
You can add canisters no problem to have more if wanted.Things like a flush are nice to make cartridges last the longest..
A built in TDS meter is really nice as you are going to find out depending what your source starts at how fast you may go through the DI media.I is the fastest spent and you need to know if it is not shooting 0...
A good float val;ve is a must..I have heard horror stories from people who sourced theirs cheaply...