Drinking Water Testing - A Primer


In June 2005, the Ministry of the Environment proposed sweeping changes to the regulation of small works in Ontario. Among the changes is a completely new regulatory framework including significantly reduced requirements for treatment and testing, transfer of the regulatory authority for this class of works to the District Health Units, and implementation of a risk-based, site specific assessment approach for treatment and testing. These changes represent a major policy shift for the Government in it's oversight of drinking water, and it will likely take some time to put into place the policy structures that are required to implement the proposed approach.

In the interim, a transitional regulation, O.Reg. 252/05 has been enacted to address the issue of safe drinking water from small works and brings into play the newly adopted policy of the MOE to limit the impact of drinking water regulation on small works. In O.Reg 252/05, owners are not required to install treatment equipment; the testing and sampling frequency requirements are significantly reduced; there is an option to post signs in lieu of testing; and the reporting requirements are simplified.

What does that mean? If you have a commercial or institutional works that serves drinking water to the public, you should review the information on O.Reg 252/05 at the sources listed below to determine what actions you need to take to come into compliance with the regulation. In some cases, works have the no-cost option of posting signs on their taps (signs are provided free by the MOE by calling 1-800-565-4923), in other cases there is a minimum requirement for microbiology testing. There are several websites that have summary information on the changes, including a summary on the MOE website (www.ene.ov.on.ca/envision/water/sdwa/reg252.htm), including detailed guides for each category of works.

In the meantime, the following is a list of common terms used in drinking water testing that would be good to be familiar with as you explore the regulations further.

Total Coliforms: The coliform group of bacteria is the most commonly used indicator of water quality. The presence of these bacteria in drinking water is indicative of inadequate disinfection in the treatment or distribution systems. It can also be an indicator of surface water infiltration, since total coliforms are widely distributed in the natural environment.

Fecal coliform: The fecal coliform group of bacteria that exhibit specific growth characteristics. The presence of fecal coliforms in drinking water may be an indication of sewage contamination. E. coli is a member of the fecal coliform group.

E. coli: Is a fecal coliform present in fecal matter and prevalent in sewage. It is a strong indicator of recent fecal pollution. Contamination with sewage shown by a high level of E. coli would strongly suggest the presence of pathogenic bacteria and viruses. Certain strains of E. coli are pathogenic (cause illness).

Heterotrophic Plate Count: A measurement of the viable aerobic bacteria content in the sample. HPC testing can be used to monitor disinfection efficiency and water quality deterioration in distribution systems and reservoirs. It is also known as Standard Plate Count (SPC).

Membrane Filtration Test: A technique for the enumeration of bacteria in water samples. In this technique, the measured volume of sample is filtered through a filter having a pore size small enough to trap the bacteria on the surface. The filter is then layered on bacterial nutrients and the organism(s) allowed to grow at a controlled temperature.

If suitable bacteria are present, a visible colony will be produced which can be counted under a microscope. The result is numerical and expressed as Colony Forming Units (CFU) per 100mL.

Presence Absence Test: A technique where the sample is used to inoculate a nutrient solution which is then incubated under specific temperature controlled conditions. Target organisms will cause a colour change, which is detected by the analyst. The result is qualitative and expressed as Present or Absent for the target organism.

Chain of Custody, C/C; CoC; the submission paperwork that must accompany any submission of samples to the laboratory; specifies client details of the sample characteristics and the testing to be performed.

EnviroTest Laboratories, and other drinking water testing laboratories in Northern Ontario, have a lot of experience with the regulations and serving the drinking water testing needs of many works throughout the North. As aggravating as the regulations can be, a good laboratory can be an indispensable partner in overcoming the information overload and staying in compliance. A good place to start is our website at http://www.envirotest.com, where links to the relevant MOE pages can help to sift the wheat from the chaff.

For further information, do not hesitate to contact one of our helpful staff toll-free 1-800-668-9878.

Richard Clara is Director of EnviroTest Laboratories in Thunder Bay and has been involved in drinking water and environmental analysis in the region for over twenty years. He can be reached via email at tba@envirotest.com

Editor's Note: The drinking water regulations mentioned in this article are outdated and this article is meant for drinking water testing knowledge only. Current drinking water regulations (O.Reg 319/08) can be found here.

This article was taken from pages 6 & 7 of NOTO's "The Outfitter" publication, Summer/Fall 2005 Issue


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