An intermediate storage unit is often used to provide a water source local to a fire which can be refilled with water from a natural source (e.g. river) or water tanker.
To fulfil this requirement, it is invaluable to have a temporary water tank which can be permanently carried with the fire fighting appliance and assembled quickly (without tools), when needed. The Japanese Fire School uses the FASTANK 5 during training of recruits in such firefighting techniques, which are reflective of standard practice around the world.