Fire hydrants are usually designed as a part of the water supply system. However, in industrial and logistics complexes, hydrants are sometimes fed by fire water supply from the sprinkler pump room. The fire water supply can also be solved by using part of the sprinkler tank volume as a fire tank. When the sprinkler pump room supplies water to the external hydrants, it is necessary to install two fire pumps.
Indoor fire hoses are an essential part of the fire safety of buildings and should not be missing in warehouses even if the building is protected by sprinklers. Hydrants are often used to extinguish fires at an early stage of development and can be used for fire fighting if sprinklers are triggered. Connection can be made from the manifold before the sprinkler alarm valves. The total water flow is increased by the hydrant draw.
External hydrants are intended as a water source for responding firefighters and are rated for larger water withdrawals. They may be supplied by their own pump or from a common combined water supply sized for sprinklers and hydrants in all operating conditions. The water supply may also be designed to feed a fire water main on the premises from which all fire water intakes are connected. Such fire water mains tend to be looped and divided into separately lockable sections. Shutoff valves on underground pipes in enterprises and logistics premises sometimes have an overhead post indicating the position of the underground valve.
The fire water tank may be shared with the sprinkler tank. It is cheaper to build a shared tank than to have one for sprinkler system and a second one for a water supply.