Residential Water Testing (Technical Bulletin)
Reporting requirements for adverse drinking water test results when a municipality takes chlorine and/or microbiological samples from plumbing in response to customer service complaints.
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Issue #5 – October 2014
This bulletin discusses O. Reg. 170/03 requirements for reporting adverse drinking water test results when a municipality takes chlorine and/or microbiological samples from plumbing in response to customer service complaints. This bulletin is applicable to regulated large and small municipal residential drinking water systems. This bulletin does not apply to lead samples.
Municipalities often take samples directly from a customer’s home. There has been confusion in the past on whether adverse test results related to these samples need to be reported to the Ministry. Municipalities have asked the Ministry to clarify the availability and proper use of the Schedule 16 exemption from reporting requirements for adverse chlorine and microbiological drinking water samples taken from plumbing solely to determine the quality of the water in plumbing.
Schedule 16 Exemption for Plumbing Samples (3.0)
When a municipality considers its reporting obligations under s. 18(1) of the Act, the following exemption may be available to it:
Paragraph 2 of ss. 16-2(2) of Schedule 16 to O. Reg. 170/03
16-2(2) Despite subsection (1), subsection 18 (1) of the Act does not apply to the following drinking water tests: …
2. A drinking water test that is conducted on a sample that was taken from plumbing, if the test is conducted solely for the purpose of determining the quality of the water in the plumbing. [emphasis added]
The Drinking Water System Regulation, O. Reg. 170/03 made under Safe Drinking Water Act 2002 (the Act) came into effect in 2003.
To help ensure safe drinking water in Ontario, this update provides clarification on how the Ministry interprets certain sections of the Act and regulations, so that all drinking water system owners/operators have a common understanding.
The reader should review the Act and regulations or consult a lawyer for answers to specific questions.
These clarifications have been approved by the Director, Safe Drinking Water Branch, Ministry of the Environment and Climate Change.
For inquiries about the bulletin contact:
Compliance, Promotion and Support Branch
Ministry of the Environment, Conservation and Parks
40 St. Clair Avenue West,
Toronto, Ontario M4V 1M2
Exemption Not Available After a Period of Flushing (4.0)
When plumbing is flushed for a period of time, the water in the plumbing is replaced with water from the drinking water distribution system. If a chlorine residual or microbiological sample is taken after a period of flushing, the Ministry will infer that that the test is being conducted to assess the quality of water in the drinking water system, not the plumbing. Any adverse test result with respect to the prescribed chlorine concentrations or microbiological parameters is reportable. See paragraphs 1, 4 and 5 of ss. 16-3(1) of Schedule 16 to O. Reg. 170/03. The Schedule 16 exemption for drinking water samples taken from plumbing solely to determine the quality of the water in plumbing is not available.
Exemption May Be Available When a Sample Is Taken Without a Period of Flushing (5.0)
Chlorine Residual and Total Coliform (TC) Indicator Tests
When a chlorine residual or TC sample is taken without a period of flushing, adverse test results may be attributed to the water within the plumbing itself. For example, a low chlorine residual result may represent a problem within plumbing rather than in the distribution system, and an adverse TC indicator test may indicate contamination of the source supply or distribution lines or microbiological re-growth within the plumbing system itself.
Therefore, the Ministry accepts that a municipality may wish to determine whether an adverse chlorine residual or TC result represents a problem solely in a consumer’s plumbing, and that the Schedule 16 exemption for drinking water samples taken from plumbing solely to determine the quality of the water in plumbing is available.
E. coli (EC) Indicator Test
The detection of E. coli indicates recent fecal contamination and is a rare occurrence within the plumbing system itself.
Therefore, an adverse test result for E. coli does not qualify for the Schedule 16 exemption for drinking water samples taken from plumbing solely to determine the quality of the water in plumbing, except in the following limited circumstances.
The Ministry may accept that a municipality has hired a licensed laboratory to conduct E. coli testing solely for the purpose of determining the quality of water in the plumbing, if there is no flushing and the municipality took a corresponding chlorine residual and microbiological sample from the distribution system (i.e. from a point near where the plumbing sample was taken, at a similar point in time).
The concurrent distribution sample results should be sufficient for the municipality to determine legally required reporting and corrective actions for the system.
Adverse test result resulting from a Plumbing sample after: Chlorine Residual TC EC Flushing Reportable Reportable Reportable No Flushing Not Reportable Not Reportable Reportable (unless corresponding distribution sample taken)
Under section 81(2) of the Act, the Ministry may require a municipality to provide documentation to show how flushing calculations were done. This may include calculations to determine how long it would take to replace the water in the plumbing with water from the distribution system.