Abstract: A water cannon adapted for controlling large crowds of unruly people in a highly effective, yet non-lethal fashion. The cannon can be mounted on an appropriate vehicle, such as an armored car, so as to make it mobile and its supporting system completely self-contained. The water cannon discharges a high velocity stream of water in a pulsing fashion. Each pulse forms a water projectile which is effective against human targets at ranges up to one hundred feet. The water can be treated with a variety of desired additives. The water cannon includes a cannon body on which is operatively mounted a nozzle for discharging the discrete coherent water projectiles. The discharge of the water projectiles is controlled by a main stage valve, which is in turn controlled by a pilot valve. A water supply reservoir and pump are provided for supplying water under pressure to the main stage valve.