a regular screwdriver will work. Fleck does make a special tool, but this is only really needed by the assemblers or guys whoe service them regularly. You need to remove the drain fitting from the drain/brine assembly, you will see that inside the drain port, there will be a plastic retainer with 4 slots in it. Insert a crewdriver blade into one of the slots and carefully unscrew the reateiner from the housing. Remove this part and the button will be easily removed. Remeber, number go toward the valve when ou reinstall the button. The button will have numbers on it that indicate the flow rate.