dfk41
I must admit, I have little experience of RO setups for drinking water, but having used RO systems for many years for my Reef aquariums - in my mind this is a very good pure/waste ratio!
in basic RO systems (e.g. 50gpd productions - gpd = gallons per day) it is not unusual to have 1:3 ratio (pure/waste) - this improves with higher production RO membranes (e.g 200gpd+) - but even then, an acceptable ratio is 1:1
so they must be doing something ‘funky’ to achieve this 3:1 ratio (recycling possibly, as suggested by Dave)
…but to me, this seems like a very good ratio
also, bear in mind the ‘waste’ water is still quite useful for household use (watering plants, cleaning, etc) so can effectively improve that ratio even further, if you collect and reuse the ‘waste’.