The purpose of an extinguishing media plan should be to supply enough media for a fire to be fully extinguished; this should include an appropriate level of resilience, including identifying a secondary supply that can be used should the primary supply fail.
Water supplies and their method of delivery to the fireground will vary depending on the size of incident but may include:
- Portable systems including backpacks, buckets, etc.
- Tanks and pump supply from emergency fire vehicles
- Continuous supply from water mains through hydrants
- Open water supplies: for example, rivers, lakes, ponds or swimming pools
In achieving suitable and sufficient water plans for any incident, sufficient physical resources should be available at the incident to deliver of water from the source to the emergency fire vehicles and from the emergency fire vehicles to the scene of fire.
A competent pump operator is essential if a water plan is to be successful. Failure of the continuous delivery of water to the fire ground can create serious hazards for frontline firefighting teams.
In normal circumstances, only fire and rescue service pumps and fire and rescue service hose should be used to deal with the incident. However, certain incident types may result in crews using other systems to support firefighting operations. For example, when firefighting on a ship, the use of on-board firefighting pumps and pipelines may be used in place of pumping emergency fire vehicles.
Estimation of water requirements
The flow rate required to deal with a particular risk and the period of time for which that flow rate must be sustained depend on many factors, including:
- The extent to which the fire is likely to have spread before firefighting starts
- The size of the building or area at risk
- The fire loading
- Environmental factors – the possibility that nearby watercourses may become contaminated
- The construction of the building – materials and compartmentation, etc.
- The need to protect adjacent risks
There are many factors to be considered, particularly with a large or protracted use of water. It may be difficult to estimate the exact quantity of water likely to be required but this should be established by incident commanders as part of their incident plan and risk assessment. For larger incidents, it may be necessary to allocate responsibility for formulating a tactical water plan to a functional water officer.
Refer to the National guidance document on provision of water for firefighting, published by the Local Government Association and Water UK in January 2007 for further information.
Distribution of water supplies
Water undertakers obtain their water from three main sources:
- River intakes
- Impounding reservoirs, containing water collected from high ground, streams and general rainfall
- Underground sources, such as wells, boreholes and springs
When establishing a water plan using hydrants, it is important that the incident commander or water officer is aware of these district metered areas through liaison with local water company specialists. This will enable them to maximise the amount of water available in the area of the incident, helping to maintain an adequate supply and ensure that the supply is not overrun, causing damage to the main. For further information on district metered areas see Section 4.2 of Fire Service Manual, Volume 1, Fire Service Technology, Equipment and Media: Hydraulics, Pumps and Water Supplies
Supplying water to the fireground
There are two fundamental methods of conveying water from distant sources to a fireground:
- Using water tenders or water carriers to maintain a shuttle from the supply source
- Relaying water over the distance using pumps and hoses
When determining which might be the most appropriate strategy, incident commanders should consider:
- The additional quantity of water needed and the time that it will be required
- The location and size of the source(s), factoring in the time of year and the distance from the fire
- The resources and equipment available
- The time required to set up operations
Emergency fire vehicles – tank supply
With the increasing diversity in modern emergency fire vehicle design, there is no standard tank size. A traditional water tender ladder or water tender typically has a tank size of 1,800 litres; however modern appliances may carry significantly different volumes of water.
Water relay
A water relay comprises a number of pumps spaced at intervals along a route between a water source and the point where the water is required.
There are two types of water relays commonly referred to and used:
- Closed-circuit water relay, in which the water is pumped through hose direct from one pump to the next
- Open-circuit water relay, in which water is pumped through hoses through portable dams placed between pumps
The principal advantage of the open-circuit water relay is that, should there be a failure of the base pump (the first pump in the water relay set into open water supply or hydrant supply); the relay can continue to maintain a flow of water to the fire.
When determining which might be the most appropriate strategy the incident commander should consider the effect on local infrastructure (i.e. the disruption to the local transport network caused by hose lines with limited crossing points.) This will be particularly prevalent where high volume pumps are used.
Water carrying or water shuttle
Water carrying or water shuttle is achieved by using a number of water tenders to collect water from the source and deliver it to the tank of an emergency fire vehicle or into a temporary open dam.
Alternatively, bulk water carriers can be used to transport water from a water source some distance from the fire scene to the fire ground and deliver it to the tank of an emergency fire vehicle or into a temporary open dam.
The advantages of using water carriers instead of a large number of conventional water tenders are:
- Fewer numbers of emergency fire vehicles are required at the incident
- Fewer personnel are required
- Total time taken to mobilise emergency fire vehicles is usually reduced
- Fewer numbers of water carrying journeys are required
- Emergency fire vehicles are not committed simply to carry water
- Operating costs for the incident are reduced
Refer to the firefighting equipment knowledge sheets for information on: