All RO systems produce reject water called concentrate that is commonly sent to the drain or reclaim system. When softened as a pre-treatment before feeding the RO system, this water is potentially the second best water source at a car wash after RO. SONNY’S Spot-Free Concentrate Saver stores and pressurizes this water for re-use, ideally suited for chemical application or elsewhere in the wash. Once you have sized the RO unit and storage tank, the concentrate saver storage tank can be sized. This tank can be above or underground, and may require an optional fresh water make-up solenoid.