The water cannon is probably best known as a police vehicle, as seen during the riots at the G20 summit in Hamburg's Schanzenviertel in July 2017. This already indicates the main areas in which police water cannons are used, namely at violent demonstrations, in street fights, for example between rival soccer fan groups, at sit-in blockades or similar occasions, to keep large groups of people under control, avert danger or extinguish burning barricades. Police water cannons are also used to protect officers involved in police operations from attacks and to secure barriers. Outside of such operations, the task of a police water cannon can also be to supply residents of disaster areas with drinking water. The police water cannon holds around 9000 to 10,000 liters of water, weighs around 25 to over thirty tons and requires a crew of up to five people. Depending on the water cannon, so-called cannon tubes throw 1200 to 2200 liters of water per minute over a distance of 50 to 65 meters. This requires a pressure of around 20 bar. In order to be protected from attacks by demonstrators, for example, the police water cannon is glazed with polycarbonate. The driver's cab is made of aluminum. Police water cannons have sloping roofs so that it is impossible to climb on them and so that thrown Molotov cocktails do not remain on them.
The fire department's water cannon is something different: this is a fire department pipe that can be placed on the ground for operation so that a specific area can be permanently watered without tying up individual firefighters. In this way, a fire department water cannon can be used to protect neighboring buildings in the event of a fire. Fire department water cannons can also be water sprayers mounted on a trailer. They do not have to be held in the hand, which would not be possible anyway due to the high water pressure. These fire department water cannons have a greater range than conventional C-pipes, for example.
