Water Testing Interpretation

What Does Your Report Mean?


Unsatisfactory Result:

A private well water sample is considered unsatisfactory, and unsafe for drinking, when the fecal coliform E. coli is present.


An unsatisfactory result indicates fecal contamination of the well. The drinking water should be boiled and corrective action should be taken to solve fecal contamination entering the well. Retesting should be carried out following appropriate corrective action.


Substandard Result:

A private well water sample is considered substandard, but not an immediate health risk, when testing reveals the presence of coliforms but no E. coli.


A substandard result indicates that surface water may be entering the well and therefore at risk of fecal contamination, or that a bacterial growth has developed within the well or plumbing system. Suitable disinfection of the well should be undertaken and the water retested to ensure there is no fecal contamination. Until disinfection is carried out and retest results are known, the water may be boiled or an alternate safe source may be used.


Satisfactory Result:

A private well water sample is considered satisfactory when coliforms are absent and the fecal coliform E. coli is absent.


A satisfactory result meets the provincial standard for the bacteriological quality of drinking water.


Occasionally, test results may be reported as “overgrowth-unable to interpret”. This is due to the presence of excessive environmental bacteria in the sample that interfere with the test. A repeat samle is suggested. If problems persist, contact an environmental health oficer or public health inspector at Service NL.


More On Water Testing

Water Testing Overview

What To Do If You Have An Unsatisfactory or Substandard Test Result?


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