"Wasteful?"
I recycle my rejection water from the unit to water my palm trees. It's as simple as not pointing my 1/4" tubing down the drain, and instead running it to an outdoor res which gravity drips onto various locations on my property with intravenous equipment that I poached from my place of occupation. Claiming RO( or RODI) is wasteful is sort of like saying alcohol causes drunk driving. Don't fault the unit, fault the human.