Water sampling guidelines:
General:
Our main objective is to assure the accuracy and precision of our results so that they will be reliable, interpretable,
repeatable and defensible.
The condition of your water sample and the sample container can affect results, for this reason we advise following
our sampling guidelines closely. Submitting your sample in an appropriate container can eliminate the need for
retesting due to possible contamination.
We stock 500mL and sterile 120mL containers and you are most welcome to collect containers prior to sampling. If
you need more that 10 bottles at a time, please contact us to ensure that we have enough bottles in stock.
Where to take water samples:
In terms of where to sample, it is very important to have a clear idea of what information you are trying to obtain. For
example, if you are only interested in the quality of water coming out of your kitchen tap, then the sampling should
take place there. However, if you have installed treatment and you want to find out how effective it is, then you may
want to take 2 samples – one from the tank (pre-treatment) and one from the kitchen tap (post-treatment).
It is not usually advisable to take a sample from a river or stream as it characteristics can change so much. Ideally
the water should be pumped into a reservoir and this should be where the sample is taken from. However if there is
no reservoir in place, try to sample when the stream or river is in its most common state. When sampling from a
stream or river, face the container upstream and allow filling gently until it is full.
How to take water samples:
- Wash your hands.
- Use the containers provided by the laboratory.
- Other containers can be used, but rinse the bottle and lid with boiling water (repeat twice).
a. The minimum sample volume requirement is 500mL per sample.
b. The minimum sample volume requirement for SANS 241 analyses is 2L per sample.
c. Please do not use milk or mayonnaise bottles. - If the sample is taken from a tap, wipe the tap edges with a tissue, and then pass a flame over the edge 2 – 3
times and run the tap for ± 3 minutes before sampling. - If you are taking the sample from a borehole, pump the borehole for 15 – 20 minutes to clear the stand pipe of
any “stale” water. - Rinse the sample bottle with the sample water, repeat twice.
- Fill the bottle with the sample water and cap.
- Keep samples out of direct sunlight.
- Keep samples cool but DO NOT freeze.
- For any microbiological analyses, deliver to Labserve within 24 hours.
- For customers who are not within easy driving distance, we suggest taking your sample(s) in the early afternoon
and sending it overnight via courier to the laboratory.
Additional notes on sample condition:
A. Microbiology:
Preferably, microbiology samples should be submitted within 24 hours post sampling.
• If samples for microbiological analysis are submitted more than 1 day post sample collection, the sample
condition will be recorded as ‘Poor’ and the customers will be advised to re-sample. The laboratory will only
continue with testing activities on such prolonged submission period samples, once the customer gives their
written consent to such activities.
• Frozen samples will be noted as such under the sample condition. The laboratory will only continue with
testing activities on frozen samples, once the customer gives their written consent.
• The minimum volume of water required for microbiological analysis is 120ml.
B. Chemistry:
Preferably, chemistry samples should be submitted within 3 days post sampling.
• If the temperature of the sample exceeds 35°C, the sample condition will be recorded as ‘Poor’.
• If samples are submitted more than three days after the collection thereof, the sample condition will be
recorded as ‘Poor’.
• Frozen samples will be indicated as such under sample condition.
• The minimum sample volume for chemical samples should be confirmed with the laboratory prior to
submission.
• For Dissolved Oxygen & Free Chlorine:
o Fill the bottle (underwater if possible), and make sure that there is no head-space in the container, and cap.
o For the analyses to be accurate, the sample needs to reach the laboratory as soon as possible, preferably
within 6 hours.
C. Organic chemistry:
Preferably, organic chemistry: samples should be submitted within 24 hours post sampling, in a glass
container with no headspace.
• Frozen samples will be noted as such under the sample condition. The laboratory will only continue with
testing activities on frozen samples, once the customer gives their written consent.
• The minimum sample volume for organic chemistry samples is 1 litre.