High- or low-velocity streams of water are commonly used as a crowd-control weapon. Typically referred to as water cannons, various types of water hoses are connected either to in-ground water supplies or to mobile bladders (often on trucks). Water cannons have been used as a crowd-control weapon in protests all over the world and continue to be used regularly, now most often as vehicle-mounted devices.
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1700s
Water cannons have been used since the early 1700s, initially for fighting fires …
… and later also for dispersing crowds or limiting access to certain areas.
1930s–1960s
Water cannons were first used for crowd control in the 1930s in Germany …
… and, by the 1960s, were in frequent use in the United States during civil rights protests.
Today
Water cannons are used as a crowd control weapon in protest all over the world …
… most often as vehicle-mounted devices.
Mechanism of action
Water cannons function by propelling streams of water towards protesters. These can be either high-pressure streams, aimed at pushing back crowds, or low-pressure streams, intended to douse. High-pressure water cannons can have flow rates of up to 20 litres of water per second, with an operating pressure of 15 bar (220 psi), and can send water 67 metres.
By comparison, a typical residential showerhead has a pressure of 3 bar (40 psi). High-pressure, high-volume water cannons can knock individuals over and push them backwards with significant force, particularly when this pressure is sustained and exerted on a large surface area.
Tear gas or chemical systems on truck-mounted water cannons, where secondary bladders holding dyes and chemicals are designed for the ejection of these chemicals within the water stream, are growing in popularity.
Coloured dyes, often semi-permanent and requiring several days and numerous washes with strong detergents to remove, have been used for more than 25 years in many places, including India, Indonesia, Israel, Hungary, Northern Ireland, South Africa, the Republic of Korea (South Korea) and Uganda. Coloured dyes have been used to humiliate and to publicly mark protesters, sometimes so that they can be arrested at a later date. Some water cannons have also been used with ultraviolet dyes to assist in delayed identification and/or arrest of protesters.
Coloured dyes have been used to humiliate and publicly mark protesters, sometimes so that they can be arrested at a later date.
Health effects
Because of the limited literature on water cannons and scarcity of medical literature on injuries, it was not possible to conduct a full systematic review of the injuries caused by water cannons. However, a review of articles identified in our systematic search of data published in secondary sources identified a number of cases of serious injury directly or indirectly caused by water cannons.
High-pressure water can cause both direct injuries, such as trauma directly to the body, and internal injuries from the force of the water stream. There are a handful of case reports that describe facial injuries such as blindness or eardrum rupture from the force of the water.
The blunt force of high-velocity water cannons can cause indirect injuries from forced falls onto the ground or obstacles. Case reports describe contusions, skull fractures and lacerations secondary to water cannon strikes. Occupational injuries to law enforcement officers during training included accidental musculoskeletal injuries from close-range exposure.
In recent years, personal reports on social media and news reports have highlighted the inherent dangers of water cannons. There are several documented cases of bone and musculoskeletal injuries and fatalities from falls and trauma secondary to the force of the water. After the publication of our prior report, Baek Nam-gi, a South Korean farmer, went into a coma after being knocked over by a water cannon and died of his injuries in September 2016.
In a similar case from May 2015, Chilean student Rodrigo Avilés suffered serious head injuries after he was knocked over by water cannons fired from a distance of less than five metres. After being in a coma, Avilés eventually recovered, but he still has seizures and other health issues.
In 30 cases of injury from water cannons in Türkiye, injuries varied in severity based on the pressure, distance and duration of exposure, as well as whether victims experienced collisions, falls or being swept away by the force of the water.
Case studies
What has changed?
In recent years, the use of water cannons has expanded in many countries around the world, as has the number of reported injuries.
Given the rise of Twitter and other social media, many injuries are reported directly by the victims. The use of malodorants, dyes and chemical irritants also appears to be expanding beyond the few countries that used these measures at the time of our 2016 report.