Water can dissolve many minerals or chemicals and transport microbiological contaminants - refer to Part 1 of this article. Testing of drinking water is common practice in Western Australia, with analytical testing designed to tell you the following:
- How safe your water is for drinking purposes?
- The levels of contamination in your drinking water
- The aesthetic quality of your drinking water.
Collection of drinking water samples should be done in a manner that limits the potential for unwanted contaminants during collection and handling of the sample to ensure an accurate representation of drinking water quality.
Collecting a drinking water sample requires the use of a set of appropriately supplied sampling bottles from a nominated NATA accredited laboratory. These pre-rinsed and sterile bottles are used to ensure that no other contaminants have been introduced into the sample. Each of the bottles in a given set will contain various size bottles and preservatives to ensure the correct preservation and sample volume for the nominated drinking water test.
Appropriate sample collection means removing contamination potential from the sample point, to ensure an accurate representation of collected sample water. This may include heat treatment of the sample point using a propane lighter to remove microbiological build up at the sample point, and the use of disposable nitrile-free gloves to be worn by the person sampling for the duration of the collection activities. These gloves should be discarded and replaced between sample points.
Samples should be stored at required temperatures, as advised by the nominated laboratory. This usually involves storage and transportation of the samples in a cooled esky for delivery. Particular analysis may also require submission of samples within designated timeframes to meet the preservation criteria of a given analysis. In some instances this can be less than 2 days. Ensuring good coordination of sampling and delivery options, particularly in remote areas is crucial in receiving accurate sample results.
For analytical Quality Assurance (QA), a duplicate sample may be collected at one of the sampling points. The Department of Environment Regulation (DER) indicates that a 1:20 ratio for collection of QA samples is appropriate to ensure data can be shown to be reliable and sample collection procedures appropriate.
By undertaking accurate and representative sampling of drinking water, an appropriate assessment of the quality of your drinking water can be defined, and analytical results relied upon.
Department of Environment Regulation. 2014. Assessment and management of contaminated sites. Contaminated sites guidelines. December 2014.
Department of Health. 2011. Standard Drinking Water Test. Delivering a Healthy WA. Government of Western Australia, Department of Health, Public Health.