When taking water samples from a stream, the filtered water samples are the priority and
should always be collected first.
You will need the site bag containing the sample bottles, and a prepared pack of syringes
and single-use filters.
Carefully place these bags on a stable base within easy reach, or in your pocket.
Ensure you are facing upstream with the water flow coming towards you.
If there is minimal flow in the stream, position yourself in the area with the best possible
flow, and avoid taking a sample from isolated ponds.
Wash your hands thoroughly in the stream.
Gloves are not strictly necessary and may make handling the containers more difficult.
Remove a syringe from the polybag and rinse it in the stream.
To rinse the syringe, fill it with water and dispose of the water downstream.
This process should be carried out three times.
Once this is done, fill the syringe up again and be ready to begin sampling.
Remove a filter from the small polybag containing clean and unused filters.
Handle it only on the edges and take care not to touch the tip or allow the filter to
become contaminated.
Carefully place the filter onto the end of the syringe, then seal and return the small
polybag to the larger bag containing the syringes.
Press the syringe lightly to release a few drops of water, and to equilibrate the pressure
between the syringe and filter.
Now remove the bottle marked ‘F/A’ from its polybag.
This should always be the first water sample you collect.
First, pre-rinse the bottle.
Remove the cap and, using the syringe, put a small amount of filtered water
into the bottle.
Replace the cap, shake the bottle, and dispose of the water.
Repeat this process three times.
When removing the cap, ensure no unfiltered water, dirt, or your finger, comes into contact
with the cap or the inside of the bottle.
Do not put the syringe, cap or bottle down onto a surface and risk contamination.
Once the bottle has been pre-rinsed three times, you may begin filling the bottle with
filtered water.
When the syringe is empty, screw the cap back onto the bottle and return it to the polybag.
It will take several syringefuls to fill the bottle.
Remove the filter, taking care again to only handle it on the edges, and refill the syringe.
Replace the filter and retrieve the partially-filled bottle from the polybag.
Continue filling the bottle.
If at any stage it is becoming harder to filter the water, do not brace the filter against
the neck of the bottle in order to force water through it.
This may rupture the filter membrane, meaning water collected is not screened
to the correct fraction.
Instead, switch to a second filter.
Always draw up the stream water from a few centimetres below the surface flow.
Ensure that samples are taken from where the water is actively flowing and avoid sampling
water that has become cloudy where the stream bed has been disturbed.
Fill the ‘F/A’ bottle to just the base of the neck and secure the cap tightly.
Now return the ‘F/A’ bottle to its polybag and remove the other bottle, marked ‘F/UA’.
Repeat the process of triple rinsing as per the previous bottle.
You can continue to use the same filter if water is passing through it freely.
Ensure any used filters are disposed of in the pre-labelled ‘dirty’ bag, as it is
often hard to distinguish between used dirty and unused clean filters.
Fill the ‘F/UA’ bottle completely, leaving minimal air space at the top,
and secure the cap tightly.
Return the bottle to the polybag with the ‘F/A’ sample and tie loosely to ensure
that both bottles remain clean.
Return this bag to the site bag.
Next, remove the largest bottle from the site bag.
This is used to collect unfiltered water, so the syringe and filters are not required.
Remove the cap and place the bottle directly into the stream for pre-rinsing.
Partially fill the bottle, replace the cap, shake the bottle and dispose of the water.
Repeat this process three times.
Now the sample may be taken.
Completely submerge the bottle in the water to ensure there are no air bubbles
in the sample.
Once the bottle is filled with water, screw on the top, ideally while it is still submerged.
Shake dry the bottle and check carefully for air bubbles before returning it
to the site bag.
If you identify any air bubbles, refill the bottle and ensure that no bubbles remain.
A second unfiltered water sample is collected in the small bottle with the black cap.
As before, rinse the bottle three times before collecting the sample.
To collect the sample, submerge the bottle and ideally screw on the cap
while it is still submerged.
Shake the bottle dry, invert and check for air bubbles.
Once again, if you identify any bubbles, refill the bottle.
Return the bottle to the site bag, ensuring that the site bag remains as dry as possible.
Now remove the unused and long polythene bag.
This is used to make an observation of the stream water colour and suspended solids content.
First, fill the bag with water from active and undisturbed flow.
Then hold it up against clear light and note the colour.
If necessary, adjust the position of the bag so that it is against clear sky,
rather than vegetation.
This will ensure a more accurate observation.
Observe and note the colour of the water: yellow, brown or colourless.
Also observe the degree of suspended solids in the bag: absent, light, moderate or high.
Return the water to the stream, and the empty polybag to the site bag.
This bag will be used later to bag up your stream sediment sample.
An observation must also be made of the stream bed material.
In order to do this, take a sample of a variety of clasts from the stream and rub them against
the skin of your forearm to create a streak.
Take note of the average streak colour and intensity: orange, brown or black.
This indicates what materials have precipitated and oxidised on the surface
of the stream bed.
Collect the polybags, ensuring they are sealed, and leave the stream with caution.