Potable water is not required; however, fresh water is required since salt water causes corrosion. Per
capita gallon/per/man/day factors for watercraft maintenance operations are difficult to estimate because
of the great variance in the ratio of force strength to vessel type and density. Watercraft requirements
are driven more by theater port facility infrastructure than by the deployed force population.
10. Water Purification, Storage, and Distribution Requirements. Once daily water requirements
have been determined, commanders and staff planners must then make a number of computations to
determine purification, storage, and distribution requirements. Planners should know the capabilities of
the water and transportation units to prepare detailed plans accurately for mission support.
a. Purification Requirement. The size and composition of the water supply section, detachment,
or team needed to provide for the total daily requirement must often be computed. To do this, the total
daily requirement is divided by the daily production capability of one purification unit. The daily
production capability depends on several factors. These include the GPH rating of the unit, type and
temperature of the water source, and the daily hours of operation. Under normal conditions, water
purification equipment is operated 20 hours per day with four hours downtime for operator and crew
maintenance. Temperature affects the production capability of purification equipment. At a raw water
temperature of 50€F, ROWPU production capability is reduced by 50 percent. Generic purification
production rates in gallons per hour are as follows:
b. Storage Requirement. Temperate, tropical, and arctic regions usually do not require large
amounts of potable water to be stored. Their nonpotable water requirements can be met by raw water
sources, and their potable water requirements can be met by the water purification section's organic
storage tanks. In arid regions, large quantities of water must be stored because such water is used for
both potable and nonpotable requirements. Brigades and divisions deployed in arid regions will have
additional storage teams assigned to handle the additional storage requirements. Raw water storage may
be needed for purification equipment if access to raw water sources are limited. To compute the total
storage requirement, determine the location and daily requirement on the battlefield. Double the daily
requirement at Corps and EAC to provide an additional day of supply at these levels. Then compute the
number of water supply companies needed to store the total requirement by dividing it by 1.6 million
(storage capacity of one water supply company in gallons).
c. Distribution Requirement. Distribution capability is the maximum overland transportation
capability using TWDS, SMFT, and the 500-gallon drums of the FAWPSS.