1 March 1997
1. PURPOSE AND SCOPE. This document provides design criteria for water storage requirements at
military facilities, gives typical design analyses for elevated tanks, standpipes, and reservoirs, and provides
guidance on the procedures to be followed in selecting sites for such storage works. The manual covers
requirements for treated water storage in the distribution system, but not the storage requirements for raw
water supplies or fire deluge systems.
2. APPLICABILITY. These instructions are applicable to all USACE elements planning and designing
water storage facilities at fixed Army and Air Force installations.
3. REFERENCES. Appendix A contains a list of references used in these instructions.
4. OBJECTIVES OF STORAGE.
a. Flow Requirements. Storage should meet peak flow requirements, equalize system pressures, and
provide emergency water supply. The water supply system must provide flows of water sufficient in quantity
to meet all points of demand in the distribution system. To do so, the source must produce the required
quantity and quality, pressure levels within the distribution system must be high enough to provide suitable
pressure, and water distribution mains must be large enough to carry these flows. It is usually inefficient
and uneconomical to construct the treatment plant and pumping stations sufficiently large to meet the
largest anticipated water demands. A water treatment plant is less efficient if flow rates through the plant
are rapidly varied. Water storage facilities are constructed within a distribution network to meet the peak
flow requirements exerted on the system and to provide emergency storage.
b. Cost. At times it is desirable to know the cost of constructing water storage for fire protection. In such
cases only the actual fire flow for the fire period will be used in establishing the proportionate share of the
total cost of storage. Cost of that portion of the storage required for concurrent domestic, industrial, or
special demands that cannot be curtailed during the fire period will not be charged to fire protection.
c. Meeting peak flow requirements. Water supply systems must be designed to satisfy maximum
anticipated water demands. The peak demands usually occur on hot, dry, summer days when larger than
normal amounts of water are used for watering lawns and washing vehicles and equipment. In addition,
most industrial processes, especially those requiring supplies of cooling water, experience greater
evaporation on hot days, thus requiring more water. The water treatment plant can operate at a relatively
uniform rate throughout the day of maximum demand if enough storage is available to handle variations in
water use. The necessary storage can be provided in elevated ground, or a combination of both types of
d. Distribution system pressures.
(1) System pressure requirements.
(a) Minimum pressures. Water distribution system, including pumping facilities and storage tanks
or reservoirs, should be designed so that water pressures of at least 280 kPa (40 psi) at ground level will be
maintained at all points in the system, including the highest ground elevations in the service area. Minimum
pressures of 210 kPa (30 psi), under peak domestic flow conditions, can be tolerated in small areas as long
as all peak flow requirements can be satisfied. During firefighting flows, water pressures should not fall
below 140 kPa (20 psi) at the hydrants, in new systems. This requirement does not constitute justification