Testing microbiological parameters in swimming pool and spa pool water.
About this Testing
Microbiological testing of public swimming pool and spa pool water is governed by NZS 5826:2010 Pool Water Quality, as detailed in the following table:
Microbiological Water Quality Criteria
Standard Plate Count (SPC)
< 200 per mL
Compliance for SPC may not be appropriate for geothermal or open air pools, depending on the environmental setting. High levels may indicate that the disinfection system is not in good working order.
Faecal Coliforms or Escherichia coli (E.coli)
< 1 per 100mL
Indicator of faecal contamination. Presence indicates the possibility of harmful gastro-intestinal pathogens also being present.
< 100 per 100mL
Bacteria that can cause skin infections and irritations, or ear and eye infections.
< 10 per 100mL
Bacteria associated with eye and ear infections when dunking the head in swimming pools, or with rashes or folliculitis on the body in spa pools.
Contamination of swimming pools or spas occurs as a result of various faecal, oral or nasal discharges and skin shedding, and usually results in the accumulation of micro-organisms, some of which are harmful to humans. Non-compliance with any of the microbiological tests in the table above should be considered along with Free Available Chlorine (FAC) and pH values, as their presence will be indicative of poor performance of the disinfection system of the pool.
Taking a Sample
When taking the sample, it is very important to follow the instructions provided. This requires a sterile container (square plastic 400mL) containing a sodium thiosulphate preservative which must not be rinsed out or discarded during sampling. The preservative is usually put into the bottle in a spray format to make bottle handling easier. The laboratory analysis must commence within with 24 hours of sampling and your sample must be under 8°C, but NOT frozen on receipt at the lab. For clients who are not within easy driving distance of the Hamilton, Christchurch or Blenheim lab sites, we suggest taking your sample in the afternoon and sending it overnight to the laboratory. Please refer to Water Collection procedures below.