This is a great option if you have VERY HARD WATER and want to extend the interval between regenerating. The FLOW CONTROL VALVE allows you to reduce the soft water flow but still keeps you warm and comfortable while showering. Then you can return to full flow for rinsing without affecting the water temperature. (Vertical = full flow; horizontal = water trickle.) This will extend the number of days between regenerating which will save water and reduce water heating costs.