TM 10-4610-310-14
WATER RECONNAISSANCE
A complete and thorough water reconnaissance and test must be performed before setting up the Lightweight
Water Purifier (LWP). The raw water source will be tested for turbidity, pH, and Total Dissolved Solids (TDS) to
determine the contents of source water that may affect the operation and/or the placement of the LWP.
This work package provides information and operating instructions for the Hanna Model HI 93703 portable,
microprocessor turbidity meter. The meter is used in the field as a hand-held, microprocessor-based, battery
operated instrument to determine the turbidity of the water. The meter has a 0 to 1000 Formazine Turbidity Unit
(FTU) range in two scales: 0.00 to 50.00 FTU and 50 to 1000 FTU.
NOTE
The FTU is identical to the other international recognized unit Nephelometric Turbidity
Unit (NTU).
Flow Rate Requirements
The LWP produces at least 75 Gallons Per Hour (GPH) of product water from any seawater source containing
20,001 to 45,000 ppm and 125 GPH or greater from any fresh or brackish surface water source containing 0 to
20,000 ppm; turbidities of up to 150 NTUs; and water temperature ranges from 32 to 95F.
An exception to the flow rate requirements is made for source waters containing contaminations such as
cyanide, lewisite, arsenic, or radioactive iodine or source water higher than 45,000 ppm. Under these conditions,
the flow rate is reduced.
WATER TREATMENT
1. Source water analysis must be made in accordance with FM 10-52 and TB MED 577.
2. Chemical injection requirement for LWP must be determined. See WP 0010 00 for instructions.
a. Coagulant injection should be made when turbidity is higher than 150 NTU.
b. If chlorine is present is source water Sodium Metabisulfite must be injected in raw water.
c.
If drawing from a seawater source, antiscalant must be injected to protect RO membranes.
d. Chlorine must be injected in product water for residual disinfection.
2. Routine inspection of units should include checking the location of raw water intake and reject hoses. Make
sure the intake is upstream from reject hoses. Leaks, cross connections, and other sources of
contamination should be inspected for and guarded against.
3. Disinfection destroys harmful organisms (pathogenic, viruses, bacteria, and protozoan) present in the water
by exposing the organisms to specific concentrations of disinfecting agents or to heat. Basic procedure for
disinfecting water is chlorination. Chlorination is the most common method of disinfecting potable water.
Sufficient chlorine is added to the water to achieve the desired Free Available Chlorine (FAC) residual after
a 30-minute contact time.
a. Calcium hypochlorite (HTH) is the preferred agent because it comes in granular form (60-75 percent
available chlorine) and has a long shelf-life
b. Sodium hypochlorite (5 percent or 10 percent). This is a liquid solution (household bleach) and may be
used in lieu of HTH. However, it is less convenient to handle, takes larger quantities to achieve the
same concentration of FAC, and has a much shorter shelf life than HTH.
c.
See WP 0010 00 for chemical injection instructions.
0005 00-1
