the good water i put in a rubbermaid container to mix the salt with it and airate it, the runoff water is still filter water and i use it in my fresh water tanks.
The clean water output of my RO/DI unit has 2 float valves. One is attached to a LARGE rubbermaid container for mixing new saltwater for water changes. The other float valve is mounted in my sump and it adds ro water for the evaporated water of the system. The ro/di waste water is run to a water drain in my house.