Drinking Water Testing – Private Citizen

Consistent with O. Reg. 671/92 of the French Language Services Act, laboratory testing information on this page is only available in English because it is scientific or technical in nature and is for use only by qualified health care providers and not by members of the public.

This page provides information on drinking water samples submitted to the Public Health Ontario (PHO) laboratory by private citizens who rely on private drinking water systems for their drinking water. Submissions are restricted to drinking water sources defined as: Potable water from any source which is protected from surface or ground water contamination, regardless of any filtration procedure and / or chemical disinfection applied, is aesthetically acceptable, and serves fewer than 6 private residences but not to the public. For analytical purposes, water passing through a point-of-use treatment device will be regarded as a private water source.

The target organisms of the test are Total Coliforms and Escherichia coli (E. coli).

For information related to water sample collection, submission and testing, please refer to our Well Water Testing webpage or contact PHO laboratory’s Customer Service Centre.


  • Added a Submitters Responsibilities section
  • Updated the following sections: Storage and Transport (store samples in the dark and prevent direct contact with ice packs) and Testing Methods (added assay performance and limitations)

Submitter's Responsibility

By submitting the water sample for testing, the submitter accepts Public Health Ontario’s methodology, and represents and warrants that the water sample was taken from the Location of Water Source indicated in the test requisition and that the information provided is true in all material respects at the time of submission. The Ontario Agency for Health Protection and Promotion assumes no responsibility for the accuracy of the information provided, the manner in which the sample was collected or the mode by which it was transported to the laboratory.

The submitter must follow the instructions provided by the laboratory for: sampling labeling, completing the chain of custody/requisition, requirements for submission, sample transport and temperature conditions, and holding time (i.e., the allowed time from sample collection until analysis).

Specimen Collection and Handling

Specimen Requirements

Test Requested Required Requisition(s) Specimen Type Minimum Volume Collection Kit

Total coliform and E. coli

Private Citizen drinking water for single households ONLY

200 mL (to the fill line on the bottle)

PHO laboratory private citizen drinking water collection kit:

Private Citizen Water – bacteriological
Item #: 390040

Submission and Collection Notes


The collection kit may be picked up at the client’s nearest PHO laboratory or public health unit or one of their affiliated kit pick up locations. 


Use the PHO laboratory water collection bottle in the kit to collect the sample and follow water sampling instructions.


Refer to the acceptance criteria in included in the instruction page of the collection kit. Ensure all gray shaded areas of the form are completed, including the full date (including the year) and time collected and if possible the optional information as well. The sample will not be tested if the required information is incomplete and/or inaccurate when the sample is received at the laboratory.

Timing of Specimen Collection

Ensure adequate time to collect and transport the sample to the laboratory.  All drinking water must be tested within 48 hours of collection in order to comply with the purposes of the Safe Drinking Water Act, 2002.3

Routine drinking water samples are accepted Monday to Friday 8:30 a.m. to 4:30 p.m. excluding statutory holidays. 


Samples will not be tested if the acceptance criteria are not met.

Drinking water that falls under one of the Ontario drinking water regulations, O. Reg. 170/034 or O. Reg. 319/085 (e.g., city water that is treated and provided by a municipal source) will not be tested by the PHO laboratory. Owner operator(s) of public drinking water systems must use licensed and accredited commercial laboratories for their routine testing.  Refer to the Ministry of the Environment, Conservation and Parks list of licensed laboratories.

Storage and Transport

Place the completed form in the plastic bag supplied and wrap it around the collection bottle with the elastic band.

Keep specimens in the dark, stored at 2 – 8 °C following collection and ship them to PHO’s laboratory inside insulated containers or in a cooler with frozen ice packs.  Arrange the samples so they do not tip and avoid direct contact with ice packs.  Frozen samples are not accepted.  Samples received at the laboratory above 25 °C will not be tested.

Submit samples as soon as possible; they must be tested within 48 hours of collection and the sample temperature needs to be below 25 °C when received at the laboratory.  Check local public health unit websites for drop off times.  Sample drop off times for the PHO laboratory are listed on the Well Water Testing webpage.

Special Instructions

Due to unforeseen circumstances, it may be necessary to refer samples to another licensed laboratory for testing, other than the laboratory to which sample was initially submitted.  For information about PHO laboratory drinking water testing licenses and accreditation visit Accreditation and Licensing.

Complete all fields on the Bacteriological Analysis of Drinking Water for Private Citizen, SINGLE HOUSEHOLD ONLY Test Requisition Form.  The collection kit may be picked up at a PHO laboratory (Note: Only 81 Resources Rd. location for the Toronto location) or public health unit or one of their affiliated kit pick up locations. 

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

Samples are routinely accepted and tested at the laboratory Monday – Friday during regular operating hours 8:30 a.m. to 4:30 p.m. For submission around statutory holidays, refer to the PHO laboratory holiday schedule posted on the PHO Well Water Testing website.

Turnaround time is up to 4 business days.

Test Methods

Each Public Health Ontario laboratory location holds a drinking water testing license from the Ministry of the Environment, Conservation and Parks (MECP), and drinking water tests limited to the individual laboratory’s scope of testing are accredited by the Canadian Association for Laboratory Accreditation Inc. (CALA) to the current version of ISO 17025. 

Drinking water samples are tested by the Membrane Filtration method modified from MECP E3407: Membrane Filtration method Using DC Agar for the Simultaneous Detection and Enumeration of Total Coliforms and Escherichia coli in Drinking Water6 for the microbiological indicators Total Coliforms and Escherichia coli (E. coli). 

Assay performance and limitations:

Total Coliforms and E. coli assay performance:

  • A multi laboratory study that included the PHO laboratory, determined the sensitivity and specificity of the method to be 93% and 91% respectively7 
  • In-house studies show that more than 90% of E. coli strains present in water can be detected using this procedure, however, false positives and false negatives can occur.  Three percent (3%) of E. coli isolates are β-glucuronide – negative.8 This method does not allow for the determination of toxigenic species of E. coli (e.g., E. coli 0157:H7)
  • Some strains of Aeromonas, can be misidentified as coliforms due to their ability to ferment lactose.9 Conversely, there are some organisms that meet the definition of a β-glucuronide negative coliform that are non-lactose fermenters.  They would be considered false negatives

Membrane filtration assay limitations:

  • Material that is larger than the pore size of the membrane filter (e.g., particulate matter or algae) can clog the membrane filter and interfere with target colony detection
  • Bacterial cells that have been stressed, e.g., exposed to adverse environmental conditions, may not survive the filtration process or may be negatively affected by the chemicals used as selective agents in the medium
  • Some non-target bacteria may release bacteriocins, proteins that can inhibit the growth of target bacteria.  High levels of toxic metals or organic compounds may become concentrated in the membrane filter and inhibit colony growth


Interpretation of the test results and any follow up actions are listed on the test report.

Clients requiring assistance with the interpretation of results or advice on the correct course of action are to contact their local public health unit and speak to a public health inspector as outlined in the Ministry of Health’s Safe Drinking Water and Fluoride Monitoring Protocol.10

Samples are not tested for other contaminants, including chemical contaminants, and therefore may be unsafe to drink even if there is no significant evidence of bacterial contamination. Consult with staff at the local public health unit for more information about testing for other contaminants.


Results are reported to the individual indicated on the requisition and not released by fax. The results are available by:

  1. Mail: The report is sent to the name and mailing address that appears on the requisition.
  2. Picking up the report at the laboratory: If this was indicated on the requisition, photo identification is required when picking up the report. A designate may pick up the report at the laboratory with photo identification and a completed Potability of Water Release form.
  3. Telephone by calling the Interactive Voice Response (IVR) 1-877-723-3426 / Teletypewriter (TTY) 1-866-828-2238 and keying in the sample barcode. For TTY calls:
    1. Call 711 with a TTY device or follow the instructions provided by the telecommunications provider to call the Relay Service Operator.
    2. Ask the operator call 1-877-723-3426 and press 1 for English.
    3. Give them the barcode number and ask them to follow the prompts.
  4. Electronic: A written request may be submitted to the PHO laboratory Customer Service. Include the timeframe of the results you are looking for, the sample barcode(s) (if available) and the location of the water source address (i.e., street address or lot and concession number, township/municipality, country and postal code).


  1. Health Canada. Canadian drinking water guidelines [Internet]. Ottawa, ON: Government of Canada; 2022 [modified 2022 Nov 28; cited 2023 Sep 21]. Available from: https://www.canada.ca/en/health-canada/services/environmental-workplace-health/water-quality/drinking-water/canadian-drinking-water-guidelines.html
  2. Ontario Agency for Health Protection and Promotion (Public Health Ontario). Public health inspector's (PHI) guide to environmental microbiology laboratory testing. Toronto, ON: Queen’s Printer for Ontario; 2021 [cited 2023 Sep 21]. Available from: https://www.publichealthontario.ca/en/Laboratory-Services/Public-Health-Inspectors-Guide
  3. Safe Drinking Water Act, 2002, SO 2002, c 32. Available from: https://www.ontario.ca/laws/statute/02s32
  4. Drinking Water Systems, O Reg 170/03. Available from:  https://www.ontario.ca/laws/regulation/030170
  5. Small Drinking Water Systems, O Reg 319/08. Available from:  https://www.ontario.ca/laws/regulation/080319
  6. Ontario. Ministry of the Environment, Conservation and Parks. Membrane filtration method using DC agar for the simultaneous detection and enumeration of total Coliforms and Escherichia coli in drinking water and ground water. E3407 Revision. Toronto, ON : Queen’s Printer for Ontario; 2022.
  7. Schop RN, et al.  Comparison of the relative recovery of Escherichia coli and Total Coliforms by Differential Coliform and Chromocult Coliform agars. Poster presented at: CALA Catalyst Conference. 2014 June 2-4; Toronto, ON.
  8. Kilian M, Bűlow P. Rapid identification of Enterobacteriaceae. II. Use of a β-glucuronidase detecting agar medium (PGUA agar) for the identification of E. coli in primary cultures of urine samples. Acta Pathol Microbiol Scand B. 1979;87(5):271-6. Available from: https://pubmed.ncbi.nlm.nih.gov/393074/
  9. Martin NH, Trmčić A, Hsieh T-H, Boor KJ, Wiedmann M. The evolving role of coliforms as indicators of unhygienic processing conditions in dairy foods. Front Microbiol. 2016;7:1549. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5043024/
  10. Ontario. Ministry of Health. Safe drinking water and fluoride monitoring protocol, 2019 [Internet]. Toronto, ON: Queen’s Printer for Ontario; 2019[cited 2023 Sep 21]. Available from: https://www.health.gov.on.ca/en/pro/programs/publichealth/oph_standards/docs/protocols_guidelines/Safe_Water_Fluoride_Protocol_2019_en.pdf
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Updated 23 Nov 2023