*TM 5-813-1/AFM-88-10, Vol. 1
Table 4-1. Water Hardness Classification.
which utilize the proposed source. Careful study of
historical water quality data is usually more productive
Total Hardness
Classification
than attempting to assess quality from analysis of a few
mg/1 as CaCO3
samples, especially on streams. Only if a thorough
search fails to locate existing, reliable water quality data
0-100
Very Soft to Soft
should a sampling program be initiated. If such a
100-200
Soft to Moderately Hard
program is required, the advice and assistance of an
200-300
Hard to Very Hard
appropriate state water agency will be obtained. Special
over 300
Extremely Hard
precautions are required to obtain representative
samples and reliable analytical results. Great caution
Softening is generally considered when the hardness
must be exercised in interpreting any results obtained
exceeds about 200 to 250 mg/1. While hardness can be
from analysis of relatively few samples.
reduced by softening treatment, this may significantly
increase the sodium content of the water, where zeolite
4-6. Checklist for existing sources of supply
softening is employed, as well as the cost of treatment.
The following items, as well as others, if circumstances
b.
Total dissolved solids (TDS). In addition to
warrant, will be covered in the investigation of existing
hardness, the quality of ground water may be judged on
sources of supply from Government-owned or other
the basis of dissolved mineral solids.
In general,
sources.
dissolved solids should not exceed 500 mg/1, with 1,000
a.
Quality history of the supply; estimates of
mg/1 as the approximate upper limit.
future quality.
c.
Chloride and sulfate. Sulfate and chloride
b.
Description of source.
cannot be removed by conventional treatment processes
c.
Water rights.
and their presence in concentrations greater than about
d.
Reliability of supply.
250 mg/1 reduces the value of the supply for domestic
e.
Quantity now developed.
and industrial use and may justify its rejection if
f.
Ultimate quantity available.
development of an alternative source of better quality is
g.
Excess supply not already allocated.
feasible. Saline water conversion systems, such as
h.
Raw water pumping and transmission
electrodialysis or reverse osmosis, are required for
facilities.
removal of excessive chloride or sulfate and also certain
I.
Treatment works.
other dissolved substances, including sodium and
j.
Treated water storage.
nitrate.
k.
High service pumping and transmission
d.
Other constituents. The presence of certain
facilities.
toxic heavy metals, fluoride, pesticides, and radioactivity
l
l.
Rates in gal/min at which supply is available.
in concentrations exceeding U.S. Environmental
m.
Current and estimated future cost per 1,000
Protection Agency standards, as interpreted by the
gallons.
Surgeon General of the Army/Air Force, will make
n.
Current and estimated future cost per 1,000
rejection of the supply mandatory unless unusually
gallons of water from alternative sources.
sophisticated treatment is provided.
(For detailed
o.
Distance from military installation site to
discussion of EPA water standards, see 40 CFR-Part
existing supply.
141, AR 420-46 and TB MED 229 for Army Projects and
p.
Pressure variations at point of diversion from
AFR 161-44 for Air Force Projects.)
existing system.
e.
Water quality data. Base water quality
q.
Ground elevations at points of diversion and
investigations or analysis of available data at or near the
use.
proposed point of diversion should include biological,
r.
Energy requirements for proposed system.
bacteriological, physical, chemical, and radiological
s.
Sources of pollution, existing and potential.
parameters covering several years and reflecting
t.
Assessment of adequacy of management,
seasonal variations. Sources of water quality data are
operation, and maintenance.
installation records, U.S. Geological Survey District or
u.
Modifications required to meet additional
Regional offices and Water Quality Laboratories, U.S.
water demands resulting from supplying water to military
Environmental Protection Agency regional offices, state
installation.
geological surveys, state water resources agencies, state
and local health departments, and nearby water utilities,
including those serving power and industrial plants,
4-2
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