Water cannon

A water cannon is a high-velocity device designed to discharge large volumes of water. These machines are capable of projecting streams over dozens of meters. Because of their power, they serve several distinct roles in society. They are essential tools for firefighting and industrial mining operations. They are also used for washing large vehicles and for riot control. Most water cannons are categorized as fire monitors. This means they are built to manage high-pressure water flow effectively.

The mechanism of a water cannon relies on high pressure and volume. To function, the device pushes water through a nozzle at a high velocity. This creates a concentrated stream that can travel great distances. In modern police versions, the operation is often remote. An operator sits safely inside a vehicle and uses a joystick to aim the cannons. For example, the Austrian-built WaWe 10.000 uses three cannons that can spray in all directions. Two cannons are positioned at the front, while one is at the rear. This allows for precise control of the water stream from within the protected cabin.

Water cannons have evolved through several different stages of technology. Early crowd control was improvised and used stationary water pumps. In 1892, Athens used pumps to create what was called a "copious artificial rain." By the 1930s, Greece transitioned to motorized firefighting vehicles. These vehicles were often manufactured by firms like Fiat and Magirus. The first true truck-mounted water cannon for riot control appeared in Germany during the early 1930s. Before these trucks existed, fireboats were the primary tool for water-based control. New York City deployed its first fireboat, Marine 1, on February 1, 1891. Los Angeles commissioned its first fireboat on August 1, 1919.

Modern water cannons are often modified with different payloads to change their effect. Many models can add tear gas to the water stream to disperse crowds. Some authorities also add dyes to the water for identification purposes. In 1997, police in South Korea and Indonesia reportedly used pink dye. In Hong Kong, police used blue dye during the 2019–2020 protests. This dye can stain surfaces, such as the steps of the Kowloon Mosque in 2019. Another specialized version involves electrified water jets. In 2004, Jaycor Tactical Systems experimented with adding salt to water. This was intended to help electricity conduct through the stream. However, these experiments used jets much less powerful than standard water cannons.

There are significant differences between water cannons and other water-based tools. A pressure washer has high pressure but the force drops quickly over short distances. Water pistols are much weaker in both volume and pressure. In contrast, industrial ultra-high pressure water jet cutters are extremely powerful. These cutters can move at 1 kilometer per second. They are strong enough to cut through granite, concrete, and even Kevlar. Because of this extreme power, industrial water use carries risks of accidental death.

Different countries use these vehicles in various ways and capacities. In Germany, the Wasserwerfer 10000 is the standard model used by riot police. These units are part of a fleet of approximately 50 vehicles. In Israel, water cannons are a major export. A company called Bet Alpha Technologies has sold them to countries like Russia, China, and the United States. Israeli police models are highly advanced. They feature a joystick, cameras, and a mine plow to push through barricades. These vehicles can spray water, paint, or gas in pulses reaching 40 meters.

The history of these machines also includes significant social impact. In the 1960s, the United States used water cannons and hoses during civil rights marches. In 1963, Eugene "Bull" Connor ordered their use in Birmingham, Alabama. The sight of water being used against protesters and children was widely viewed as shocking. This imagery helped shift public sympathy toward the civil rights movement. In Australia, the New South Wales Police Force bought a cannon in 2007. However, it was never used for civil unrest and was eventually converted into a water tanker for fire departments.