Remember, in a RO system the membrane does the heavy lifting. The first two filters help scrub chlorine and solids to help extend the life of the membrane. Filters after the membrane are to polish the water for taste. Including adding an alkaline minerals, if you wish.
(now you can make your own Kangen water!. those who don’t know Kangen is a >$4,000 machine to make alkaline water. sold through multilevel marketing pitches)
The UV light is not necessary for city water, maybe well water. IMHO
