The Canadian Water Quality Index (CWQI) is an effective method to rate the water quality and determine its suitability for drinking purposes. CWQI measures a wide variety of parameters of water quality and then cumulatively translates them into one score.

The CWQI method requires a group of parameters that have drinking water objectives that have been set either by the Canadian government or a province to ensure that the water intended for human consumption.

Health-Related Standards: shall not contain disease-causing organisms or unsafe concentrations of toxic chemicals.

Aesthetic Objectives: should be aesthetically acceptable and palatable.

Operational Guidelines: should not contain undesirable concentrations of parameters that, if not controlled, may negatively affect the efficient and effective treatment, disinfection, and distribution of water

The CWQI calculates three factors based on these objectives:

1. the number of parameters that fail their objective,
2. the proportion of samples that fail their objectives,
3. the magnitude of any failures

A summary of results comes in two charts. First one shows CWQI and the second one shows which and how parameters influence CWQI.

The sample example provided has a CWQI of 68 (out of 100). The quality is FAIR.

The My Water Quality Report Card also provides a detailed summary of the parameters tested, why each parameter is important, and treatment options. This information can be found in Appendix A of each report card.