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Canadian Association for Laboratory Accreditation Inc.

Building Laboratory Excellence

Clarification on Acceptable Methods for Coliform Analysis

July 4, 2002
Dear Member:

The Ontario Ministry of Environment and Energy (MOEE) has provided CAEAL with clarification on acceptable methods for coliform analysis when laboratories are analyzing samples under Ontario Regulations 459/00 and 505/01, and we in turn, are passing this information on to members and assessors.

A laboratory can apply for accreditation for any validated method under the SCC/CAEAL program. However, when analyzing drinking water samples under Ontario's Regulations 459/00 and 505/01, specific requirements must be met. These specific requirements are as follows:

1. Regulation 459/00 clearly identifies in Table A of Schedule 2 that testing for microbiological parameters must include:

2. Likewise, Section 8 of 505/01 states that a sample must be analyzed for,

3. It is not acceptable to extrapolate the finding of zero coliforms on a coliform test to a numerical result of zero E. coli, unless a method has been specifically designed and validated for that purpose, as would be indicated in the method title, the stated purpose and the reference source.

Analysis for Escherichia coli or fecal coliforms must be done in addition to analysis for total coliforms. The MOEE is in the process of preparing a technical brief, clarifying acceptable methodology for coliform analysis under the drinking water regulations, so laboratories will be receiving more detailed clarification in the near future. We will ensure that all assessors in the program receive this information.

Member laboratories are responsible for ensuring that they comply with all appropriate regulations. This includes choosing methods that meet the requirements of these regulations. CAEAL's role is to ensure that the member laboratory is technically competent to perform these tests. CAEAL has an obligation to advise laboratories if any nonconformances related to regulations are observed during the course of an assessment.

For a copy of the referenced regulations, see the MOEE web site at

CAEAL and the Standards Council of Canada are committed to working with CAEAL members and the MOEE to ensure communication between all parties.

If you have any questions, please do not hesitate to contact me.

Yours truly,
Colleen M. Cotter, Assessments Manager


Dr. John Lynch, MOEE
Mr. Pat Paladino, Standards Council of Canada