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200 Chapter 6 Water Distribution Systems: Components, Design, and Operation
Table 6.1 Number and Distribution of Fire Hydrants

Maximum Distance
Average from Any Point on Street
Fire-flow Minimum Number Spacing between or Road Frontage
d
Requirement (gpm) of Hydrants Hydrants a,b, c (ft) to a Hydrant (ft)
1,750 or less 1 500 250
2,000–2,250 2 450 225
2,500 3 450 225
3,000 3 400 225
3,500–4,000 4 350 210
4,500–5,000 5 300 180
5,500 6 300 180
6,000 6 250 150
6,500–7,000 7 250 150
7,500 or more 8 or more e 200 120
Conversion factors: 1 ft 0.3048 m; 1 gpm 3.785 L/min.
a Reduce by 100 ft (30 m) for dead-end streets or roads.
b Where streets are provided with median dividers, which can be crossed by firefighters pulling hose lines, or where
arterial streets are provided with four or more traffic lanes and have a traffic count of more than 30,000 vehicles per
day, hydrant spacing shall average 500 ft (150 m) on each side of the street and be arranged on an alternating basis
up to a fire-flow requirement of 7,000 gpm (26,500 L/min) and 400 ft (122 m) for higher fire-flow requirements.
c Where new water mains are extended along streets where hydrants are not needed for protection of structures or
similar fire problems, fire hydrants shall be provided at spacing not to exceed 1,000 ft (3,800 m) to provide for
transportation hazards.
d Reduce by 50 ft (15 m) for dead-end streets or roads.
e One hydrant for each 1,000 gpm (3,800 L/min) or fraction thereof.

The choice of pipe sizes depends on occupancy of the properties along mains
(whether residential, commercial, or industrial), their water uses, and the fire risks.
Hazards at refineries, chemical plants, and lumber yards require special consideration.
According to the International Fire Code (IFC; 2006), fire hydrants are required to be
provided where a building is more than 400 ft (122 m) from a hydrant, except for buildings
equipped with automatic sprinkler systems for which the distance requirement is 600 ft
(183 m). A 3-ft (914-mm) clear space is required around the hydrants.
The minimum number of fire hydrants and their average spacing has to be within the
requirements listed in Table 6.1. The placement of hydrants should be chosen in such a
way that the maximum distance of all points on streets and access roads adjacent to a
building is not more than the distance specified by the IFC as shown in Table 6.1.

6.3 SYSTEM CAPACITY
The capacity of distribution systems is dictated by domestic, industrial, and other normal
water uses and by the standby or ready-to-serve requirements for firefighting. Pipes should be
able to carry the maximum coincident draft at velocities that do not produce high pressure
drops and surges. Velocities of 2 to 5 ft/s (0.60 to 1.50 m/s) and minimum pipe diameters of 6
in. (150 mm) are common in North American municipalities. Capacity to serve is not merely
a function of available rate of draft; it is also a function of available pressure. The water must
rise to the upper stories of buildings of normal height and must flow from hydrants, directly or
through pumpers, to deliver needed fire streams through fire hoses long enough to reach the
fire. If there were no fire hazard, the hydraulic capacity of distribution systems would have to
equal the maximum demand for domestic, industrial, and other general uses.