Monitors are essentially high capacity water jets used for fighting a wide range of varied fire hazards. Both portable and fixed types are available and variations allow for them to be aimed either manually or remotely. They also exist in a number of sizes that vary in water capacity (measured in litres or gallons per minute) and achievable distance or ‘throw’ (measured in metres or feet/yds).

The nozzle of the monitor is usually adjustable to change the water flow from fog or wide beam to jet or straight beam to meet the immediate situation needs and increase the flexibility of usage.

Foam concentrate can also be added to the water (either upstream or in some cases through the monitor itself); this means monitors are often the method of choice for delivering a large amount of foam accurately to an area in the shortest time and from a safe distance.