Thompson Rivers University
Thompson Rivers University

Water Quality

Water quality is the term used to describe the characteristics of water; it’s physical, chemical and biological attributes.

The federal government has established guidelines for water quality for both aesthetic and health concerns. Provincial regulations set out the frequency for testing for chemical, physical, and microbial content, and monitoring is required to ensure the water’s potability.

The process for ensuring high-quality water within a water system involves:

  • testing
  • monitoring
  • evaluating the test results

Water Testing

No matter what the source, water can be contaminated by chemicals and living organisms. Testing water that is meant for human consumption is critical.

To ensure that the water you are providing meets guidelines, it must be tested in a certified laboratory and the results must be compared to accepted standards.

Testing for Chemicals

A chemical test of your drinking water is essential and should be done at least once every five years.

To give you an idea of what to expect in terms of water quality, government agencies that look after water quality in your area may be able to provide you with information about the type of chemicals in your water. If not, you may find that a neighbour or a previous owner has done a chemical test.

Laboratories that do chemical testing are listed in your telephone directory. Most labs have a “drinking water package” that analyzes for common chemicals. Such labs will ship you sampling bottles along with instructions for water collection and shipping.

Testing for Living Contaminants

Microbiological testing is more complicated than chemical testing, because the water must be kept cold and needs to reach the lab within 30 hours. The lab will provide you with instructions and sampling bottles.

Tests for microbiology on untreated surface water sources may not always be informative. Living things may be absent one day but at a hazardous level the next day due to upstream contamination.

It is critical to monitor treated water frequently for dangerous living microorganisms.


Monitoring Water Quality

Checking the quality of a drinking water system is a critical part of providing safe water and an important part of owning and operating a small water system.

Monitoring and comparing water chemistry with the accepted standards for health and aesthetic quality ensures the correct treatment options are selected when necessary. Scheduled, routine checks can help in identifying potential sources of contamination.

Many things can affect the quality of the water you distribute:

  • Water quality at the source may vary at any time. This is especially true of surface water sources.
  • Water quality tends to deteriorate as the water moves through the system; pH, temperature, taste, odour, colour, and bacteria may be affected.
  • Contaminants can enter the system through leaks, breaks, and cross-connections.

Therefore, it’s important to obtain water samples regularly and from various locations throughout the distribution system. For help in identifying changes in water quality, develop a Water Quality Monitoring Program for your water distribution system.

Water Quality Monitoring Program

This is a written document that outlines how you ensure your water is safe to drink. In this document, you should write down the details of how you monitor your water system; the who, what, when, where, why, and how. For instance:

  • Is monitoring done manually or automatically?
  • Are there any customer complaints that might indicate quality problems*?

* If you find quality problems in the system, immediately activate your Emergency Response Plan.

Part of your Emergency Response Plan involves reporting any problems. Reporting is communicating operating information to those who need to know such as water users and health authorities.

A report might include details about chemical, biological, and usage problems. Maintaining an up-to-date Monitoring Program document means you will be prepared to report valuable information in an emergency.

Monitoring Schedule

An important part of your monitoring program is the monitoring schedule. This outlines the frequency with which the different parts of the water system need to be checked.

The frequency of monitoring depends on:

  • the importance of a component to the operation of the system
  • the likelihood the component will change or fail

You should customize the monitoring routine for your water system, taking into account its complexity and size. This routine can include automated monitoring equipment and daily, weekly, and periodic manual monitoring.

Continuous Monitoring

Some water systems need equipment capable of performing continuous monitoring because of concerns about:

  • UV light intensity
  • high chlorine levels
  • incoming turbidity levels

Failure of continuous monitoring systems to perform up to standard, and/or a significant deterioration of water quality can become a threat to water users. You must take immediate action to correct these problems.

Daily or More Frequent Monitoring

Where continuous monitoring equipment, such as a continuous chlorine analyzer, is not available (e.g.,), manual methods of testing are required. These tests are necessary for those activities that are more likely to cause a threat to water users should quality levels not be maintained.

Weekly or More Frequent Monitoring

A number of monitoring tasks are less urgent than others. You need to do these on a routine, but not daily, basis. For example, you need to check the amount of chlorine that remains in the chemical feed tank.

Less Frequent Monitoring

Some monitoring tasks only need to be done every now and then, but are still a necessary part of the operation of the water system. For example, you should periodically check your reservoir security.


Evaluating Water Quality

Health Canada’s “Guidelines for Canadian Drinking Water Quality” is the reference used to check water potability in many parts of Canada.

Parts of “Guidelines for Canadian Drinking Water Quality” are also published online as “Supporting Documents.” This information is available free of charge at the Health Canada website.

Other water quality authorities

There are many other regional, national, and international authorities that set standards for drinking water quality. Some of these are:

Aesthetic vs Health-Related Guidelines

Often the guidelines listed in drinking water standards are separated into aesthetic concerns or health-related concerns. Some guidelines have both values.

Aesthetic guidelines

These are related to the consumer’s acceptance of the water for drinking and other domestic purposes and commonly include:

  • taste
  • odour
  • appearance

Health-related guidelines

Levels are based on the potential harmful effects to those drinking the water over long periods of time and at levels in excess of standards. Significant safety factors are often built in when setting standards.

*NB: For some guidelines—especially microbiological ones—even short-term exposure to water that does not meet standards may be unsafe.

Ground water should be chemically tested at least every five years to look for changes in quality and to determine if the aquifer has been contaminated.

*NB: When in doubt, test. If you think that there is a problem with the quality of your water, whether surface water or ground water, get it tested.

Those Nasty Bugs

Regular testing is necessary to ensure that potentially disease-causing microbes are not present in the water you supply, because severe health consequences may result.

Check with your local health authority for requirements regarding how often you must test your water. Compare your test results to government standards for the microbial quality of the water.

*NB: Any amount of coliform bacteria detected in the sample requires the water to be treated with the appropriate method.

Surface water sources must be treated regardless of coliform test results.

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