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As an ‘evergreen’ document the PHI Guide is revised and updated to reflect current changes in field of microbiology laboratory testing and regulations. Printed versions of this document should be checked against the Public Health Ontario website to ensure the most recent version is being referenced.

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Public Health Inspectors Guide
Water Sample Analysis

Water Sample Analysis

Water sample testing detects bacterial indicators of contamination:

  • in drinking water and non-potable sources (i.e., sewage, pools, spa, and recreational beaches)
  • for investigations linked to clinical illness

Public Health Inspectors can review requirements for testing before submitting samples to PHO.

Microbiological Analysis Drinking Water Analysis Drinking Water Research Laboratory Acceptance Criteria Reporting and Interpretation of Test Results Water Status Codes and Associated Interpretation Statements

Microbiological Analysis

PHO Laboratory performs microbiological testing of water samples for the detection of bacterial indicators of contamination and specific pathogens in water. Each water sample is tested for specific indicators according to the water source.

If testing is required on a water source that is not listed in the PHO Laboratory water testing menu below, or testing is needed to identify specific etiological agents in water related to a laboratory confirmed clinical case or outbreak investigation, boards of health are asked to consult with the microbiologist, or designate, overseeing the water testing program prior to sample submission.

Sample collection requirements, sample handling, shipping conditions, test information including testing frequency, turnaround times and reporting limits are dependent on the specific water source. Samples will not be processed if the requisition is not completely and accurately filled in when received at the laboratory; and a new sample and completed form will be required to be submitted. [Click on individual testing links for test directory details – see below.]

For specific etiological agent requests, please contact the PHO Laboratory Customer Service Centre at 416-235- 6556 or toll free 1-877-604-4567.

For general information related to sample collection, labelling, storage, transportation and chain-of- custody of drinking water samples that fall under the Drinking Water Systems Regulation (Ontario Regulation 170/03) and Small Drinking Water Systems (Ontario Regulation 319/08), refer to the Ministry of Environment, Conservation and Park’s Practices for the Collection and Handling of Drinking-Water Samples.

Drinking Water Analysis

Important Information Related to Drinking Water Analysis

Type of Drinking Water System

The type of drinking water system identified on the requisition triggers specific notification requirements. Laboratories have an obligation to report test results as outlined in section 18 of the Safe Drinking Water Act, 2002 for drinking water samples submitted under an Ontario drinking water regulation O. Reg. 170/03 Drinking Water Systems or O.Reg. 319/08 Small Drinking Water Systems. The details are outlined in the Drinking Water – Official Agencies Test Information Sheet.

Public health inspectors may collect drinking water samples in accordance with the following sections of the Health Protection and Promotion Act (HPPA): Section 13, Section 41, Subsections (1), (2), (4), and (5) which include drinking water systems that are not captured by a specific regulation(s), but where the public has access to the water, and are the subject of an investigation under the Health Protection and Promotion Act (HPPA).

These may be considered ‘drinking water systems’ in which drinking water samples must be analyzed at a licensed laboratory using licensed drinking water testing methods, unless the example is entirely a plumbing system.

The table below provides examples of drinking water systems that fall outside the scope of the Safe Drinking Water Act, 2002, Drinking Water Systems Ontario Regulation 170/03 and the Health Protection and Promotion Act, Small Drinking Water Systems Regulations O. Reg. 319/08. Consult with Ministry of Health, Environmental Health Policy and Programs, Health Protection and Surveillance Policy and Programs Branch (MOH-EH) for direction on drinking water system classifications.

Completing the requisition and submitting the sample according to Instructions For Official Agencies Submitting Water Samples to the Public Health Ontario Laboratory will help to ensure samples are accepted.

EXAMPLES OF DRINKING WATER THAT FALL OUTSIDE ONTARIO DRINKING WATER REGULATIONS

Situation Example
Drinking water supplies that do not meet the specific criteria of the Safe Drinking Water Act 2002 or Health Protection and Promotion Act drinking water regulations
  • Seasonal campsite with fewer than 6 water connections, camps in unorganized territory, certain recreational camps, rental cabins with fewer than 6 units using the same water supply, etc. These are camps in which buildings are used to accommodate five or more employees who are employed in mining work, lumbering work or any other labour work in territory without municipal organization (R.R.O. 1990, Regulation 554).
  • Raw water that it is not for human consumption and is not distributed to the public.
Facilities in the following circumstances
  • Serviced by private drinking water systems that require health unit approval for licensing or funding approval: Funeral homes, group and boarding homes, homes for special care, migrant farm workers, etc.
Food premises in the following circumstances
  • Small food take-out and convenience stores where there is no direct access to drinking water by the patrons, temporary food service facilities, farmers markets, etc.
  • Special event food premises or mobile food vending vehicles
Outbreak investigations
  • Testing of a drinking water system as part of an outbreak investigation (e.g., E. coli O157:H7, Legionella, Salmonella, etc.).
Private individual well water supplies
  • Enteric disease follow-up
  • Assisting with addressing/identifying water safety concerns
  • Complaints
  • Landlord and tenant matters whereby samples are taken of the private water supply for the issuance of a section 13 order for  a violation of section 20 under the HPPA
  • Treatment devices for samples taken to assess the ability of a newly installed treatment process at a premise
Water Containers
  • Water haulage trucks (testing may be required as part of an inspection)
  • Private building water coolers
  • Commercial bottled water/water bottling facilities
  • Vending machines that dispense water, i.e. “Bottle your own water”
  • Cisterns not supplying systems regulated under the Safe Drinking Water Act, 2002 or the Health Protection and Promotion Act

Chain of Custody

The chain of custody must be maintained for drinking water samples collected under Ontario drinking water regulations (i.e., O. Reg. 170/03 Drinking Water Systems or O. Reg. 319/08 Small Drinking Water Systems).

For drinking water indicated as “HPPA O. Reg 319/08” or “SDWA O. Reg 170/03”, there are two ways to maintain the chain of custody:

Situation Action
Courier - Indirect delivery of the sample to the laboratory
  • If the person collecting the sample cannot deliver the sample directly to the laboratory:
    • Place a signed and dated "Regulated Water Seal" (refer to Appendix B: Laboratory Submission Forms) up and over the cap of the sample in such a way that the two ends of the seal are attached to the shoulder of the bottle, and the midpoint of the seal is stuck to the top of the cap.
    • The sample is sent to the laboratory with a completed requisition according to the sample transport instructions in the test directory – test information sheet.
In person - Direct delivery of the sample to the laboratory
  • If the sample is delivered directly to the laboratory by the submitter, complete the following fields in the “For Regulated Drinking Water or Legal Samples” section of the requisition:
    • The printed name of the person relinquishing the sample to laboratory personnel
    • The signature of the person relinquishing the sample
    • Date and time the sample(s) is relinquished
  • The sample is sent to the laboratory with a completed requisition according to the sample transport instructions in the test directory – test information sheet.

Compliance versus Audit Samples

Owner/operators of O. Reg. 170/03 or O. Reg. 319/08 drinking water systems are required to follow their respective directive as determined by the outcome of the risk assessment performed on the drinking water system and, if sampling is required, use a licensed commercial laboratory for their testing.

The exception is O. Reg. 319/08 small drinking water systems that supply Ontario Parks; routine compliance samples are analyzed by the PHO Laboratory.

Boards of health may sample regulated drinking water systems as part of an audit; however, they should refrain from routine monitoring of these drinking water systems.

Drinking Water Sample Hold Time

Drinking water must be analyzed in accordance with a test method listed in the Ministry of the Environment, Conservation and Parks (MECP) “Protocol of Accepted Drinking Water Testing Methods” according to the Drinking Water Testing Services regulation O. Reg. 248/03.

PHO Laboratory uses modified versions of the MECP methods; namely, E3407 Membrane Filtration Method Using DC Agar for the Simultaneous Detection and Enumeration of Total Coliforms and Escherichia coli in Drinking Water and E3408: The Spread Plate Method for the Enumeration of Aerobic, Heterotrophic Bacteria in Drinking Water. These methods include a sample hold time of 48 hours. For results to be suitable for the purposes of the Safe Drinking Water Act, 2002, samples must be tested within the hold time.

Etiological Agent Testing

A Public Health Inspector or designate under the authority of the Medical Officer of Health may collect water samples for identification of an etiological agent (e.g., Legionella spp., Salmonella spp., etc.) from drinking water systems if required for investigational purposes or outbreak situations. On the Bacteriological Analysis Water - Multiple Sample Requisition for Official Agencies, these samples must be identified as “Non-Regulated”, “HPPA Regulated Premises”, or “Private Residence”, and marked as an “Outbreak Investigation” with the outbreak/investigation number, etiological agent and clinical case identification (e.g., iPHIS, PHO Laboratory barcode identification). Alternatively, complete all sections of the Environmental Microbiology Investigation Requisition with appropriate information to ensure accurate tracking of the sampling and complete all fields as outlined on page 2 of the form.

Drinking Water Submissions under a Provincial Officer’s Order or Approval (Directive)

For samples requiring analysis for a bacteriological health related parameter not included in Ontario Drinking Water Quality Standards Ontario Regulation 169/03; e.g., Heterotrophic Plate Count (HPC) or Background, and submitted under a Provincial Officer’s Order or Approval (Directive), from a regulated drinking water system, please contact the PHO Laboratory Customer Service Centre and ask to speak to the Program Coordinator Drinking Water Testing or designate.

Drinking Water Research

The Drinking Water Testing Services regulation O. Reg. 248/03 outlines the requirements related to drinking water quality research (e.g., scientific studies, including special audits or surveys to assess drinking water quality).

If board of health personnel wish to engage in a study involving drinking water (e.g., to identify trends associated with ground water contamination in various geographic areas, etc.) contact PHO Laboratory Customer Service Centre and ask to speak to the Program Coordinator, Drinking Water Testing.

Research projects must be reviewed by the microbiologist overseeing the PHO Laboratory Environmental Microbiology program and approval must be granted by the PHO Laboratory Research and Project Review Committee before research begins.

Laboratory Acceptance Criteria

The accuracy of the test results may be affected by collection, handling and shipping. Submit water samples in a timely manner to the PHO Laboratory. Water samples that do not meet the acceptance criteria may not be accepted by the laboratory. A new sample may be submitted with a new requisition. The acceptance criteria are outlined below.

Description Acceptance Criteria

Submitter
  • Water samples must be submitted by an authorized submitter:
    • Official Agencies: Local board of health or an Ontario Park under the Ministry of Natural Resources and Forestry (MNRF). Requests for testing by any other organization (e.g., other public health partners or Ontario Ministries) will require approval from the Director Quality, Regulatory Affairs and Customer Service and microbiologist overseeing the water testing program, or designate, prior to submission.
    • Private drinking water systems (e.g., well water): Private citizen submissions of samples collected from a “single household” and serves fewer than 6 private residences but not the public.

Sample Type

Sample Requisition
  • The sample must be received with a requisition that is complete and accurate.
  • A unique identifier is used to link the sample with the requisition:
    • For Official Agency water samples, the sample barcode or barcode number must be present on both the requisition and the sample when it is received at the laboratory. For treated ice samples, a unique identifier is written on the sample bag and the requisition; they must match.
    • For Private Citizen drinking water samples, a unique identifier, e.g., the submitter’s name can be used as the unique identifier to link the requisition and the sample; however, samples are accepted without a unique identifier when the sample is received at the laboratory with the requisition secured around the bottle.
  • Water samples for identification of an etiological agent (e.g., Legionella spp., Salmonellaspp., etc.):
    • These samples must be identified as “Non-Regulated”, “HPPA Regulated Premises”, or “Private Residence”, and marked as an “Outbreak Investigation” with the outbreak/investigation number, etiological agent and clinical case identification (e.g., iPHIS, PHO Laboratory barcode identification).

Sample Collection
  • Water samples must be collected in PHO Laboratory water collection bottles.
  • Drinking water samples must be collected from the cold water tap and not the hot water tap.
  • Treated ice samples must be collected in a sterile plastic bag with wire closure.
  • Sufficient amount of sample for the analyses is required (i.e., 200 mL unless otherwise specified in the test directory – test information sheet).
  • Drinking water samples must be aesthetically acceptable; i.e., clear, colourless and odourless, and does not contain debris or substances that interfere with the test.
  • For Private Citizen drinking water submissions, only requisitions with a version number of 3743-44 (01/01) or newer are accepted.

Sample Transport
  • The sample container must be secure and not broken or damaged when received at the laboratory.
  • Samples should be stored and transported at temperatures between 2 and 8 °C following collection. Drinking water samples must be less than 25 °C but not frozen when received at the laboratory. For details on sample transport for public beach, recreational water facility or public pool/spa refer to the test directory – test information sheet.

Sample Hold Time
  • Drinking water samples must be sent to the laboratory as soon after collection as possible since they must be tested within the hold time for the test as specified in the test directory – test information sheet for the analysis required.
  • Non potable water (e.g., public beach, public pool/spa, recreational water facility, sewage, etc.) must be tested within one calendar day of collection.

Reporting and Interpretation of Test Results

The following tables outline the reporting and acceptable limits for potable and non-potable water testing. Refer to Appendix D : Water Testing Fact Sheets for interpretation and additional details on Background or Non-target bacteria, Campylobacter spp., Coliforms, Escherichia coli, Heterotrophic Plate count (HPC), Legionella spp., Pseudomonas aeruginosa, Salmonella spp. and Staphylococcus aureus.

 

POTABLE WATER

OFFICIAL AGENCY – POTABLE / ICE-TREATED

Testing Type Reporting Limit Acceptable Limit

Background or Non-target bacteria (CFU / 100 mL)

 0 to *NDOGN/ NDOGT At the discretion of the MOH. Only reported on Regulated drinking water samples submitted under a “Provincial Officer’s Order” or “Approval (Directive)”.
Total Coliforma  (CFU / 100 mL) 0 to > 80 0
Escherichia colia  (CFU / 100 mL) 0 to > 80 0
Heterotrophic Plate Count (HPC) (CFU / 1 mL) < 10 to > 3.0 x 103, **NDOGHPC < 500

*NDOGN - No Data Overgrown with non-target/NDOGT - No Data Overgrown with target

**NDOGHPC - No Data Overgrown heterotrophic plate count

OFFICIAL AGENCY – BOTTLED WATER

Testing Type Reporting Limit Acceptable Limit
Total Coliforma  (CFU / 100 mL) 0 to > 80 0
Escherichia colia  (CFU / 100 mL) 0 to > 80 0
Heterotrophic Plate Count (HPC) (CFU / 1 mL) < 10 to > 3.0 x 103, *NDOGHPC < 500
Pseudomonas aeruginosa 
  • (CFU / 100 mL): 0 to > 100
  • (CFU / 50 mL): < 2 to > 200b
 0
Staphylococcus aureus
  • (CFU / 100 mL): 0 to > 100
  • (CFU / 50 mL): < 2  to > 200b
 0

*NDOGHPC - No Data Overgrown heterotrophic plate count

PRIVATE CITIZEN – PRIVATE DRINKING WATER SYSTEMS

Testing Type Reporting Limit Acceptable Limit
Total Coliforma  (CFU / 100 mL) 0 to > 80 ≤ 5
Escherichia colia  (CFU / 100 mL) 0 to > 80 0

a An overgrown sample; that is, crowding and/or confluent and/or non-identifiable microbial growth on a plate, is considered an adverse result. When there is an overgrown condition and there is no evidence of Total Coliform or E. coli, NDOGN - No Data Overgrown with non-target is reported. The water may be unsafe to drink. When there is an overgrown condition and there is evidence of Total Coliform and/or E. coli, NDOGT - No Data Overgrown with target is reported. The water is unsafe to drink.

b When 50 mL is analyzed.

 

NON POTABLE WATER

OFFICIAL AGENCY – PUBLIC BEACH WATER

Testing Type Reporting Limit Acceptable Limit
Escherichia coli  (CFU / 100 mL) < 10 to > 1.0 x 103 ≤ 200

OFFICIAL AGENCY – SUSPECTED SEWAGE CONTAMINATION

Testing Type Reporting Limit Acceptable Limit
Escherichia colia  (CFU / 100 mL) < 1.0 x 103 to > 1.0 x 106 Not Applicable

OFFICIAL AGENCY – RECREATIONAL WATER FACILITIES, PUBLIC POOLS/SPAS

Testing Type Reporting Limit Acceptable Limit
Background or Non-target bacteria (CFU / 100 mL) Only reported if NDOGN/NDOGT Not Applicable
Total Coliforma  (CFU / 100 mL) < 2  to > 160 < 2
Escherichia colia  (CFU / 100 mL) < 2  to > 160 < 2
Heterotrophic Plate Count (HPC) (CFU / 1 mL) < 10 to > 3.0 x 103, *NDOGHPC Appendix D: Water Testing Fact Sheets
Pseudomonas aeruginosa
  • (CFU / 100 mL): 0 to > 100
  • (CFU / 50 mL): < 2 to > 200b
 < 10
Staphylococcus aureus
  • (CFU / 100 mL): 0 to > 100
  • (CFU / 50 mL): < 2 to > 200b
 < 50

a An overgrown sample; that is, crowding and/or confluent and/or non-identifiable microbial growth on a plate, is considered an adverse result. When there is an overgrown condition and there is no evidence of Total Coliform or E. coli, NDOGN - No Data Overgrown with non-target is reported. When there is an overgrown condition and there is evidence of Total Coliform and/or E. coli, NDOGT - No Data Overgrown with target is reported.

b When 50 mL is analyzed.

*NDOGHPC - No Data Overgrown heterotrophic plate count

Water Status Codes and Associated Interpretation Statements

Status Code Interpretation
0 Not yet tested
1 No significant evidence of bacterial contamination
2 Significant evidence of bacterial contamination 
3 UNSAFE TO DRINK, evidence of fecal contamination
4 No Data:  Overgrown with Non-Target 
5 The sample was taken from an unprotected source, such as a lake or river
7 The sample was too old
8 The bottle was received broken or damaged
10  Aesthetically unacceptable - The appearance or odour makes the sample   unacceptable as drinking water
11 The requisition was received separated from the sample bottle
12 The sample was not collected in the proper bottle
13 The sample was received frozen
14 The sample was collected from a hot water tap
15 Insufficient sample was submitted
17 The sample leaked in transit
18 The sample was collected from a source located outside of Ontario
19 The sample was collected from a municipal water supply
20 Insufficient information was supplied on the sample
21 Not tested for some other reason
22 No Data:  Overgrown with Target
24 Sample received was very warm upon receipt 
25 Bottled water submitted
26 Interfering substances in the sample
27 Unique identifier missing
28 Outdated collection kit received
29 Unauthorized submitter
30 Laboratory error
50 Technical difficulties with the barcode
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customerservicecentre@oahpp.ca

Updated 16 Aug 2019
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