Challenges, benefits and pitfalls of the independent laboratory process

During 1998 Sydney's drinking water supply system experienced three contamination events in quick succession. These events were revealed by routine monitoring, which indicated the presence of large numbers of Cryptosporidium and Giardia in raw and treated water. Questions were raised regarding the validity of the results produced by Sydney Water's laboratory, Australian Water Technology. In response to the incident a NSW Government Inquiry was carried out which made a range of recommendations, one of which was that "A suitably qualified independent laboratory should be established to provide accurate data for regulatory authorities." The NSW Department of Health (DOH) was given the responsibilty for interpretation and implementation of this recommendation. The role of Independent Laboratory was awarded to the Australian Water Quality Centre (AWQC) and monthly program of duplicate sample analysis was established. The implementation of the program and interpretation of the results have provided a challenge for all parties involved. A protocol was developed which defined conditions under which differences in results from the two laboratories were to be investigated. Over the time period of the Independent Laboratory process there has been only one occasion where a difference between results, as defined by the protocol, has been seen. The process has provided additional assurance of quality control procedures for the laboratories. The future role of the process will need to be readdressed in light of the results of the previous 18 months and as changes in the area of testing methodologies occur.