A lot of shit is sterile. Sterile is not a qualifier for drinking. (Yes I know you’re fucking around)
A brand-new, unopened bottle of bleach is sterile, too.
We were given a 5 stage RO system with a 2 gallon pressure tank. The intention of it, was to make water for a saltwater aquarium that we'd planned on setting up for a few years. We WERE in the process of amassing infrastructure, but this past year has REALLY kicked the shit out of us. So my point is, the system is mounted on the wall in the basement, but NOT hooked up to water yet. Still need a few more fittings.
So to clarify, I'm not a Waterologist, but what I have learned so far is that the first 4 stages are for filtering ALL the shit/crap/corruption out of the water, to make it 'pure' to then add "Sea salts and stuff" that one purchases to replicate seawater for fish and corals to survive. (including feeding them and monitoring water 'things 'n stuffs' often.)
But, the 5th stage of the system is a 'polishing' cartridge, which then feeds to the pressure tank, which then feeds to the faucet. That polishing cartridge is a use-uppable device that puts 'human body necessities' back into the water, for consumption. It then sits in the tank (identical to a hydraulic receiver) and is plumbed up to a separate tap at the sink to be filling glasses or what-have-you and is pressured by the bladder in the tank.
I'm led to understand that there is the possibility of adding a pump for the purpose of "back-flushing" the filters, to reduce the cost of replacing them. I don't know yet what the costs of said filters are, as we haven't used any yet. Balance that with the cost of water to do so. As it is, the whole process is run by the city water pressure, and our system is rated for 75 gallons per day. (it is a VERY small system, about the size of two shoe-boxes stacked side-by-each--pressure tank not included)
Now, that's it for the home system AS I KNOW IT, but that don't mean at all that I don't have learning to do, when I actually hook it up. Everything I've just said is "as I understand it" and my memory is for-shit, so it's up to all you waterologists to bonk me upside the head where I'm wrong.
I'm always up for learning, but I got to have it written down, otherwise it never happened to begin with.