Watermaker workings and quality. Educate me.

[dgasmd]

Trying to learn a little on how these units are put together, how they work, and product water quality.

I've used and built a pretty good RO/DI unit in the past for a large/complex reef aquarium system, so at least I know how those work, their principles, pre-filters needed/used, product water quality expectations, waste water, etc. What I don't know is how any of this relates to the units used or designed for boats. Since I am assuming the water quality one would expect (assuming equal to tap water at home) is far from 0 PPM, I have no idea of expectations.

So, can someone briefly and in a simplistic way a 4 y.o. can understand talk me through the different stages or pre-filters, pump, membranes, discharge, typical daily outputs, and product water quality?

Thanks in advance.