CENTRAL WATER
Standard Operating Procedure
SOP 205
COLLECTION OF SAMPLES
FOR MICROBIOLOGICAL
EXAMINATION
1. Purpose
This procedure describes the requirements of an operator to correctly undertake the collection
of water samples for microbiological analysis by an external laboratory.
2. Scope
This procedure is applicable to all water sampling from reticulation, streams, reservoirs or
bores.
3. Responsibility
3.1
Operations Manager – shall ensure that staff adheres to this procedure.
3.2
Coordinator Water Quality Team – shall ensure that:
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3.2
Water Quality Team Member – shall:
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4.
Samples are taken on time;
Associated paperwork is filled out correctly; and
the Water Quality Team member has enough time to complete samples and to
have them delivered to the courier for delivery to laboratory.
Sample bottle remains sterile while sampling; and
Sample is taken from correct location.
Procedure
4.1
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Preliminaries
Read associated paperwork
Check required amount of sample bottles
Associated paperwork is completed.
Delivery sticker is prepared for esky
Supply of ice or freezer bricks for bottle storage during transport
Chlorine Residual Test Kit
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4.2
pH Test Kit.
Activity
Use only sterile bottles for microbiological analysis. Sterile 500ml plastic bottles will have a
red dot on the outside of the container and an unbroken seal on the lid.
4.2.1 Tap Samples
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Place some ice or pre-frozen fridge bricks in esky before taking samples.
If several types of samples are to be taken (microbiological, chemical etc) from
the same point, the microbiological sample should be taken first.
Make sure that the tap is supplying from a service pipe that is directly connected
with the water main.
Sample from only frequently used taps, e.g. do not collect samples from houses
that are unoccupied, or from schools during holidays.
Do not sample from a tap with external fittings such as anti-splash nozzles, rubber
tubes, hoses or filters, etc.
Clean inside and outside of tap carefully with a clean cloth. Pay particular
attention to collection of grease inside nozzle.
Turn tap on hard, allow water to run to waste for 1-2 minutes to flush interior of
nozzle and discharge any stagnant water from the service pipe. If there are any
leaks between spindle and gland, tap must not be used for sampling.
Turn off tap.
STERILISE tap by burning the inside and outside of its nozzle with a blowtorch
until the tap is too hot to touch (this should only take 20-30 seconds).
NOTE: Please specify whenever taps could not be flamed, e.g. on Total Fire Ban days.
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Allow tap to run a few moments until cool water is being delivered.
Unscrew lid and hold in fingers until sample is collected, i.e. DO NOT put lid
down. As the inside of the bottle is sterile, be careful not to touch inside of bottle
or inside of screw cap lid.
DO NOT RINSE the bottle before sampling. The small amount of liquid already
in the bottle is Sodium Thiosulphate, which neutralizes any residual chlorine,
which may be present in the sampled water.
Fill bottle with a gentle flow, leaving about 2cm of air space at the top of the
bottle. Fill bottle directly from the water source i.e. DO NOT use any other
containers.
Replace screw cap lid.
LABEL sample ON SITE and place in iced esky.
If supply is chlorinated or chloramminated do the Chlorine Residual Test on
site and enter the results on the information sheet. Test water directly from tap
or storage, not from microbiological sample bottle.
Fill in the information sheet on site carefully and replace in plastic bag
provided. Completed forms must accompany sample to laboratory.
4.2.2 Sampling From a Stream Or Reservoir
The aim is to obtain a sample representative of water that will be supplied to customers. It
is best to sample from a tap on the outlet main, but if only a dip sample is possible:
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Take the sample as close as possible to the outlet.
Take the sample as far away from the bank as possible in order to avoid
contamination from the bank. This is best done by using a sampling stick.
If using a sampling stick:
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Make sure the sampling stick is clean and dry.
Secure the bottle to the sampling stick.
Remove the lid from the sampling bottle.
Submerge bottle about 30cm below surface and hold in current if present, or
else move it slowly forwards horizontally (not back and forth), always
sampling water that has not been touched by the stick.
Replace lid.
Remove bottle from sampling stick and label.
If not using a sampling stick:
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4.3
Hold bottle about 30cm below surface and hold in current if possible, or else
move it forwards horizontally (not back and forth), always sampling water that
has not been touched by the hand.
Monitoring Requirements
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If necessary, replenish ice before despatching samples. Samples are to be kept
around 4°C until they are analysed. Samples should never be frozen.
Attach laboratory address label to top of esky (See Water Quality Coordinator
or Environmental Engineer for appropriate laboratory address).
Ensure samples reach laboratory as soon as possible and at least within 24
hours of sample collection.