CAUTION
TM 5-6630-215-12
disintegrate the toughest metal.
These germs,
bacteria, and minute
toxic particles remain within it in a suspended state.
When ingested
they affect taste and smell;
can be harmful or deadly poisonous to the
body’s organs, muscle tissue,
brain cells and nervous system.
Water,
to be used, must be restored to the drinkable state commonly referred
to as potable water.
Potable water can contain certain measured
amounts of inclusions which medical and other evaluations have deter-
mined can be tolerated by the body mechanisms.
The operator will
test the available water and measure these inclusions to determine
whether or not they are within these limits (table 2-8).
b.
Water Cleansing Systems.
There are various methods and systems
to restore or to make water which is acceptable for human consumption.
These are covered in other manuals.
c. Water Samples.
Methods for collecting, measuring and pre-
paring water samples are described and illustrated.
The Glossary
should be referred to for definitions of vocabulary and abbreviations
used in the text.
Some meanings of terms and methods of lab-ware use,
common to both the Preventive Medicine and Engineer Sets are set forth
below.
The shelf life of reagents and standards may be
significantly shortened if they are exposed to
direct sunlight
, extremes of heat, or moisture.
By protecting them from these environmental con-
ditions,
maximum shelf life will be gained.
2-3.
STABILITY OF REAGENTS AND STANDARDS.
There is a useful lifetime
for any chemical preparation.
Each bottle or container has imprinted
on the label the manufactured lot number and expiration date.
It is
recommended that occasional checks of the reagents be made by per-
forming tests
with standard solutions.
If the results compare
favorably,
tests can be conducted with confidence.
If the result does
not agree,
it may be due to an incorrectly performed procedure, a
deteriorated reagent, or even a defective standard solution.
2-4.
TAKING WATER SAMPLES.
Water samples collected for analysis
should be collected in such a way as to provide the most representa-
tive sample possible.
In general, they should be taken near the
center of the vessel or duct and below the surface. Use only clean
bottles, beakers, etc.
for collecting samples and rinse the container
several times with the water to be sampled.
Samples should be taken
as close as possible to the source of the supply to minimize the effect
of a distribution system.
Enclosed water systems should be allowed to
run for a sufficient time to flush the system and the sample container
should be filled slowly with a gentle stream to avoid turbulence and
air bubbles.
Water samples from wells should be collected after the
pump has run long enough to be delivering water that is representative
of the ground water feeding the well.
2-2
Change 3
