First, please make sure the manual flush kit is in the closed position. Secondly, for every gallon used the system rejects 3-4 gallons of water depending on the water quality, outside temperature, and pressure. This is standard in all RO/DI systems regardless of the brand. The rejected water is simply the waste water which is not fit to pass the filtration phases.
This can be reduced by 80% after installing a Aquatec Patent Permeate Pump which makes the waste water 1:1. Another option is to add another membrane depending on your GPD. We recommend the permeate pump as it’s the most cost effective solution in the long run.