how much water does the system use to operate ?

It wastes about 3 gallons for every gallon of purified water it produces.

The efficiency/recovery rating can be found on the Performance Data Sheet which is located at whirlpoolwatersolutions.com under product manuals.

Between 4 to 5 gallons per gallon of filtered water. Yes a lot of water but in my case my water is only usable for washing dishes, laundry and watering the yard with out going thru this R.O., I cant even cook with my water. Going thru this R.O. I can cook with it, and the water tastes great. I have my own water well. I go thru a sediment filter into the water softener that feeds the entire house (I bought from Lowes and works great) then I installed the R.O. under my kitchen sink. everything works great. I have extremely hard water, that's the reason for the softener.