*TM 5-813-1/AFM-88-10, Vol. 1
CHAPTER 3
CAPACITY OF WATER-SUPPLY SYSTEM
3-1. Capacity factors
3-3. System design capacity
Capacity factors, as a function of "Effective Population,"
The design of elements of the water supply system,
are shown in table 3-1, as follows:
except as noted in paragraph 32, should be based on the
"Design Population."
Table 3-1. Capacity Factors.
Effective Population
Capacity Factor
3-4. Special design capacity
5,000 or less
1.50
Where special demands for water exist, such as those
10,000
1.25
resulting from unusual fire fighting requirements,
20,000
1.15
irrigation, industrial processes and cooling water usage,
30,000
1.10
consideration must be given to these special demands in
40,000
1.05
determining the design capacity of the water supply
50,000 or more
1.00
system.
3-2. Use of capacity factor
3-5. Expansion of existing systems
The "Capacity Factor" will be used in planning water
Few, if any, entirely new water supply systems will be
supplies for all projects, including general hospitals. The
constructed. Generally, the project will involve upgrading
proper "Capacity Factor" as given in table 3-1 is
and/or expansion of existing systems. Where existing
multiplied by the "Effective Population" to obtain the
systems are adequate to supply existing demands, plus
"Design Population." Arithmetic interpolation should be
the expansion proposed without inclusion of the Capacity
used to determine the appropriate Capacity Factor for
Factor, no additional facilities will be provided except
intermediate project population. (For example, for an
necessary extension of water mains. In designing main
"Effective Population" of 7,200 in interpolation, obtain a
extensions, consideration will be given to planned future
"Capacity Factor" of 1.39.) Capacity factors will be
development in adjoining areas so that mains will be
applied in determining the required capacity of the supply
properly sized to serve the planned developments.
works, supply lines, treatment works, principal feeder
Where existing facilities are inadequate for current
mains and storage reservoirs. Capacity factors will NOT
requirements and new construction is necessary, the
be used for hotels and similar structures that are
Capacity Factor will be applied to the proposed total
acquired or rented for hospital and troop housing.
Effective Population and the expanded facilities planned
Capacity factors will NOT be applied to fire flows,
accordingly.
irrigation requirements, or industrial demands.
3-1
Previous Page
