A pushbutton valve assembly for regulating water flow from a water supply to a point of use such as a bubbler head of a drinking fountain. The valve assembly includes a valve body adapted for mounting onto a suitable housing panel or the like, and includes an internal valve cartridge for on-off control of water flow. A pushbutton is rotatably carried by an escutcheon ring mounted rotatably onto an exposed outboard end of the valve body, and this pushbutton is axially movable between depressed and non-depressed positions for on-off operation of the valve cartridge. The pushbutton and the escutcheon ring include respective pairs of axially open wrench ports which can be axially aligned upon appropriate pushbutton rotation to accommodate reception of a tool such as a spanner wrench for rotatably removing the escutcheon ring from the valve body, thereby exposing the valve cartridge for service or replacement.