[FlyingShawn]

P.S. RO/DI makes about 4 gallons of waste for every gallon of good water (once again depending on your unit),.. Not 100.

Whiskey

I think he was referring to how quickly the waste adds up if you're making more than a couple gallons of RO. Using your 4:1 ratio, you'd only need to make 25gal of RO to create 100gal of waste water.