several times with the water to be tested and then fill
with a minimum of splashing.
When sampling surface supplies, fill chemically
cleaned raw water sample containers with water from
the pump discharge ONLY after the pump has operated
long enough to flush the discharge line. Take the
sample from the pond, the lake, or the stream at the
intake depth and location with a submerged sampler.
Submerged samplers are equipped with automatic or
manual valve systems that permit the collection of
water at the desired depth.
Take samples inside a treatment plant from
channels, pipe taps, or other points where good mixing
is obtained. At some Navy installations, special sample
taps are provided for this purpose.
Distribution System Taps
In the case of taps on a distribution system, let the
tap run long enough to draw water from the main
before taking samples.
In obtaining samples for bacteriological
examination, avoid contaminating the bottle, stopper,
or sample, because contamination often causes a
potable water supply to be reported as nonpotable.
Follow these precautions and get valid results.
Use only clean, sterilized bottles furnished by the
medical department of the installation or another
qualified laboratory. If bottles are not available from
these sources, sterilization may be carried out in
emergencies. The tops and necks of sample bottles
with glass closures should be covered with metal foil,
rubberized cloth, or heavy impermeable paper or milk
bottle cover tops before sterilization. Before sterilizing
the sample bottle to be used for a chlorinated water
sample, place 0.02 to 0.05 gram of thiosulfate,
powdered or in solution, into each bottle to neutralize
the chlorine residual in the sample. Keep the
sterilization temperature under 393°F (200°C) to
avoid decomposition of the thiosulfate.
Sampling from a Tap
When sampling from a tap, heat the outlet with an
alcohol or gasoline torch for a few seconds to destroy
any contaminating material that may be on the tip of
the faucet. Occasionally, extra samples may be
collected without flaming the faucet to determine
whether certain faucet outlets are contaminated.
Flush the tap long enough to draw water from the
main. Never use a rubber hose or another temporary
attachment when drawing a sample for bacteriological
examination from the tap.
Next, without removing the protective cover,
remove the bottle stopper and hold both the cover and
the stopper in one hand. Do not touch the bottle mouth
or the sides of the stopper. Fill the bottle without
rinsing (to avoid loss of thiosulfate). Replace the cap
and fasten the protective covering carefully.
Sampling from Lakes, Ponds,
Streams, and Pools
When collecting samples from standing water,
remove the stopper as above, and plunge the bottle,
mouth down, and hold it at about a 45° angle at least 3
inches below the surface. Tilt the bottle and allow air to
escape and fill, moving it in a direction away from the
hand holding it, so water that has touched the hand
does not enter the bottle. Discard a quarter of the water
and replace the stopper.
When collecting a sample from lakes or ponds,
take the water 25 feet or more from the shore (from
boat or pier) and preferably in water at least 4 feet deep.
Do not collect the sample at the shore.
A stream sample should be collected where the
water is flowing, not from still areas. In a meandering
stream, collect the sample where flow velocity is
normal. Use the procedure given above for standing
When collecting water from a swimming pool,
take the water from the side of the pool near the deepest
part. Sample the pool while it is in use, preferably
during the heaviest bathing load. Use the bottle
containing thiosulfate. Fill according to the sampling
procedure given above for standing water.
To ensure accurate results of water testing when
collecting water samples, you should take all
precautions to ensure that the samples are not in
To obtain a proper sample from a well, you
should take what action first?