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A water cannon is a device that shoots a high-pressure stream of water. Typically, a water cannon can deliver a large volume of water, often over dozens of metres / hundreds of feet. They are used in firefighting and riot control. Most water cannon fall under the category of a fire monitor.
Water cannon were first devised for use on fireboats. Extinguishing fires on boats and buildings near the water was much more difficult and dangerous before fireboats were invented. The first fireboat deployed in Los Angeles was commissioned on 1 August 1919. The first fireboat in New York City was Marine 1, deployed 1 February 1891. There may have been other fireboats elsewhere even earlier.
Fire trucks deliver water with much the same force and volume of force as a water cannon, and have even been used in riot control situations, but are rarely referred to as water cannon outside this context.
Riot control 
The first truck-mounted water cannon were used for riot control in Germany in the beginning of the 1930s.
Truck-based water cannon were used widely in the United States during the 1960s for riot control. Although they were safer than a combination of firearms, tear gas, and batons, their use as a non-lethal riot control mechanism has fallen out of favor in the United States.
Since then, other higher-tech non-lethal weapons have been developed for domestic use. Whether these newer weapons are more effective and safer than water cannon remains controversial. Their competing vendors disagree as to which is more effective and safer.
Water cannon designed for riot control are still made in the United States and the United Kingdom, but most products are exported, particularly to Africa and parts of Asia. In the case of the UK there are only 6 water cannons, all held by the Police Service of Northern Ireland; their use in England and Wales would require the authorisation of Parliament (or in the case of Scotland, the Scottish Parliament). The most modern versions do not expose the operator to the riot, and are controlled remotely from within the vehicle by a joystick. These vehicles can carry 8,000 litres (1,800 imp gal) of water, and have a delivery rate of 15 litres per second (200 imp gal/min). The water can be delivered as a continuous stream, or in pulses; as a hard jet or as a spray.
The State of New South Wales in Australia purchased a water cannon in 2007, with a view to using it during an APEC meeting in Sydney that year. It was not used. It was the first purchase of a water cannon in Australia.
Water cannons are still in use on a large scale in Germany, Northern Ireland, Belgium and other parts of Europe. The annual riots on 1 May in Berlin, the Schanzenfest fair in Hamburg, which regularly ends in riots, or other demonstrations, are usually accompanied by water cannon, which support riot police. German communities use their water cannon in hot summers to water public parks.
Water cannons in use during the 1960s, which were generally adapted fire trucks, would knock protesters down and on occasion, tear their clothes.
Anecdotal reports indicate that people can walk away from an encounter with a water cannon with serious internal injuries such as a ruptured spleen. If such injuries are ignored, death could occur later. A high pressure modern water cannon can achieve pressure of up to 30 bars (3,000 kPa) which can result in broken bones.
On 30 September 2010, during a protest demonstration against the Stuttgart 21 project in Germany, a demonstrator was hit in the face by a water cannon. The eye injuries thus inflicted on the man resulted in near-complete loss of eyesight. Graphic imagery was recorded of the event, sparking a national debate about police brutality and proportionality in the use of state force.
According to a report issued in the United Kingdom, using plastic bullets instead of water cannon was justified because the latter "are inflexible and indiscriminate", although several people had previously been killed or seriously injured by plastic bullets.
Media effect 
The presence of the media at riots has had a significant impact on water cannon use. There is much pressure on police departments to avoid bad publicity, and water cannon often play badly in the press. It is considered that this is a likely reason that they are not used more often in certain countries.
Confrontations that took place in the era of the American Civil Rights Movement where water cannon were used by authorities to disperse crowds of protesting African Americans, has led to the demise of water cannon in the United States.
Alternative payload 
In 1997, pink dye was reportedly added to the water used by Indonesian police to disperse a riot. The implication is that they might use this mark to make it easier to arrest rioters later. The United Kingdom, which had sold the water cannon to Indonesia, condemned this practice, (although the Royal Ulster Constabulary had used a water cannon with purple dye during The Troubles in Northern Ireland) but later approved the sale of further water cannons to them. Most modern water cannon are also capable of adding tear gas to the stream.
Electrified water cannon 
Jaycor Tactical Systems was experimenting, in 2004, with additives (salt and additives to reduce the breakup of the stream into droplets) that would allow electricity to be conducted through water. They have demonstrated delivery from a distance of up to twenty feet (6 m), but have not yet tested the device on people.
Although referred to as an electrified water cannon, this experiment involved a water jet much less powerful than a water cannon.
Other types 
Water cannon differ from other similar devices in the volume of water delivered in a given time, the nozzle speed, the pressure that it is delivered at, and to a lesser extent the total volume that can be delivered. They are also generally portable. The method of employment is also important in labelling a device a water cannon. Nevertheless, the distinction between a water cannon and other similar devices is fuzzy. For example:-
- Pressure washers generally produce an extremely high pressure stream where the power of the stream drops off significantly over a very short distance.
- Water pistols and other toys deliver much less water at a much lower pressure with a much lower volume of water.
- Ultra high pressure water jet cutters are used to cut a wide variety of materials including granite, concrete (see hydrodemolition), ceramics, fabric and even Kevlar. One such cutter delivers 55,000 psi (380 MPa) through a nozzle 0.003 inch (8 micrometres) in diameter at 1 kilometre per second. This can cut a person in half at close range. There are reports of accidental deaths involving the industrial use of high-pressure water.
Croatian Police water cannon CVT-6000
German police water cannon
French National Police water cannon
Water cannon of the French National Police deployed to prevent rioting following Nicolas Sarkozy's election, 6 May 2007
Demonstration against G8 meeting, 5/9/2007
A Dutch police water cannon.
Moscow OMON riot control water cannon police vehicle "Lavina-Uragan" on Ural-532362.
Internal troops ABS-40 "Lavina" riot control water cannon on BAZ-6953 chassis
Water cannon vehicle of Police of Panamá, friendly named "Pitufo" (Smurf).
Other meanings 
The name "watercannon" has also been used for:-
- Similar land vehicles used for firefighting
- Various large toys, for example images 
- Waterjet in hydraulic mining
- A type of railway wagon used to remove fallen leaves off the track: e.g. seen at Alexandra Palace on 25 October 2003
- Tool for powerwashing large construction equipment. See riveer.com for images, details and video
See also 
- "Fedor Lapshin (Федор ЛАПШИН), ''Vodyannoye ohlazdhenie'' (Водяное охлаждение)". Trucks.autoreview.ru.
- "Wet v wild: riot squad shows off its $700,000 weapon". Sydney Morning Herald. 21 August 2007. Retrieved 2008-12-26.
- "0712 – WATER CANNON". Parliament.nsw.gov.au. Archived from the original on 12 March 2008. Retrieved 2008-12-26.
- "Wasserwerfer-Opfer bleibt auf einem Auge blind" [Water cannon victim blinded in one eye] (in German). 13 October 2010. Archived from the original on 23 March 2011. Retrieved 23 March 2011.
- "Blinded Stuttgart 21 protestor wants apology". 28 December 2010. Archived from the original on 23 March 2011. Retrieved 23 March 2011.
- "List of People Killed by 'Rubber' and 'Plastic' Bullets". 14 March 2011. Retrieved 26 August 2011.
- Fred Khoroushi (interviewee, President Alpine Armoring, Tony Long (writer), Bruce Nash (creator) (2003-03-13). "Non-Lethal Weapons". Modern Marvels. Season 9. Episode 9. History Channel. http://www.alpineco.com/video/history_channel/index.html.
- Indonesia and East Timor: Arms and security transfers undermine human rights. 3 June 1997. Amnesty International 
- "Jaycor Water Cannon". Archived from the original on 26 June 2004. Retrieved 2011-07-18.
- "How a Water Jet Machine Works". JET EDGE Waterjet Systems.
- By V.P. Silva. "Rechargeable Watercraft With Motorized Water Canon". The UberReview.
- [dead link]
- "Water Cannons". Raging Rapids.
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