CMPT as a Quality Partner for Water Testing Laboratories

Over the years, CMPT collects a great amount of data on the performance of Water Testing Laboratories. As a proficiency testing provider, CMPT is in an ideal position to identify common issues affecting testing laboratories.

As a Quality Partner, CMPT can provide information on overall performance of Water Testing Laboratories and identify trends that can be acted on.

We invite you to read an abstract of an upcoming publication on the data collected by CMPT on Water Testing Laboratories performance.

Helping ensure the quality of drinking-water through implementation of a proficiency testing program for microbiology: A mixed methods evaluation of water testing laboratory performance across Canada

Mahfuza Shreya1, Esther Kowk1, Caleb Lee1, Lucy Perrone1

1 Canadian Microbiology Proficiency Testing


The principal public health concern for microbial safety in drinking water is pathogens derived from fecal contamination1. Consideration of water sources, targeted

Digitally colorized scanning electro micrograph of E. Coli. Photo Credit: U.S. National Institute of Allergy and Infectious Diseases (NIAID)

treatment, and laboratory contamination testing is a requirement of municipalities across Canada outlined by the Canadian Drinking Water Quality Guidelines (CDWQG). Testing is mandated and regulated across the ten provinces according to established contamination parameters2. Most Canadian laboratories performing microbiological testing of drinking water are accredited to the international standard ISO/IEC 17025 – Testing and calibration laboratories. As part of Canada’s testing quality assurance scheme, these laboratories must participate in external quality assurance (EQA) programs, including proficiency testing (PT) programs, to ensure credibility in accurate laboratory detection and characterization of regulated microorganisms. Monitoring drinking water testing at regular intervals is a necessary risk management strategy to control the quality of microbial risk assessment performed by community health authorities. The Canadian Microbiological Proficiency Testing (CMPT) program has implemented a drinking-water microbiology PT program since 1996.

This study presents and discusses the implications and learning points of a drinking-water PT program geared towards rural and metropolitan testing sites in British Columbia and across Canada, accounting for four years of uninterrupted program implementation and evaluation. This review includes EQA program design, population service/catchment area, frequency of challenges, testing methods employed, and assessment accuracy. CMPT’s drinking water EQA program provided challenges shipped to subscribing tested laboratories three times per year. Each challenge consisted of 4 samples containing unknown concentrations of pure E. coli, Enterobacter sp., or negative samples. Responses from participants were assessed for result accuracy based on the method of testing. The aggregate data was analyzed using statistical methods outlined by the ISO/IEC 17043 – Conformity assessment guidelines3 and summarized into a report sent to participants. These reports served as educational feedback for testing sites to evaluate the quality of their testing. During this evaluation period, the number of drinking-water testing facilities decreased, yet performance in proficiency testing has remained consistently accurate. In summary, the drinking-water proficiency testing program has contributed, and continues to contribute, to an increased quality of drinking-water testing across Canada. This study highlights the importance of EQA programs for monitoring laboratory functions and quality performance at various levels of the public health system.


1 Guidelines for drinking-water quality: fourth edition incorporating the first and second addenda (2022). World Health Organization, Geneva, Switzerland.

2 Health Canada (2022). Guidelines for Canadian Drinking Water Quality—Summary Tables. Water and Air Quality Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, Ontario, Canada.

3 ISO/IEC 17043:2010: Conformity assessment – General requirements for proficiency testing (2010). International Organization for Standardization, Geneva, Switzerland.

Posted in Article, Environmental Microbiology