The user attaches a hose to the fire hydrant, then opens a valve on the hydrant to provide a powerful flow of water, on the order of 350 kPa (this pressure varies according to region and depends on various factors including the size and location of the attached water main). This user can attach this hose to a fire engine, which can use a powerful pump to boost the water pressure and possibly split it into multiple streams.

It is a water supply with a sufficient pressure and flow delivered through pipes throughout a building to strategically located network of valves for fire-fighting purposes.

In some circumstances, water from a reticulated fire hydrant system can also be shared with other safety measures such as automatic fire sprinkler systems or fire hose reels.