Domestic Water Quality

Author: H.G. Peterson
Copyright © 1999 by Agriculture and Agri-Food Canada-Prairie Farm Rehabilitation Administration

What is domestic water quality?

Water required for household use is called "domestic water". Rural users often have two treated water sources in-house. One or several taps are designated for drinking water and receive the most extensive treatment (this can include distillation or reverse osmosis as final treatment steps). All other uses fall under domestic non-potable water, which simply means that the water may not need to meet all the drinking water quality criteria applied to the drinking water taps. In cities, municipal water treatment plants are designed to supply homes with a domestic water quality that meets drinking water quality guidelines.

What is drinking water quality?

Drinking water should not contain disease-causing microorganisms (pathogens) or harmful chemicals, and should be clear, colourless, and odourless.

What are drinking water quality guidelines?

To ensure that drinking water meets the above criteria, Canada has negotiated a set of guidelines with the provinces (Guidelines for Canadian Drinking Water Quality). It is the responsibility of each province to formulate their own guidelines, but the provinces will typically adopt the Canadian Guidelines with only minor modifications.

Some provinces (Alberta and Quebec) have taken parts of the Guidelines for Canadian Drinking Water Quality and made them law (which in turn make them regulations rather than guidelines). In these provinces, it can therefore be a criminal offense to distribute water that does not meet regulations. This is, in fact, similar to most industrialized countries in the world where drinking water is regulated.

In Saskatchewan, the Canadian Guidelines have been adopted with only some minor modifications. Saskatchewan Environment and Resource Management implements these guidelines for municipal supplies (communities) and Saskatchewan Health implements them for rural water supplies. It should be noted that the rural user bears the ultimate responsibility for on-farm water quality.

In Canada, the mandate for setting drinking water quality guidelines rests with the provinces. This is highly unusual in the industrialized world. For example, in the United States, the federal government sets drinking water quality regulations. In Europe, drinking water regulations are set by the European Union (comprising 15 different countries) and individual nations implement the regulations (if regulations are exceeded, the European Union can fine the offending country).

Are drinking water quality guidelines in Canada the same as other countries?

No. The United States and Europe implement drinking water quality regulations that are substantially different from Canada. The United States implements the most stringent microbial control in the world for municipally distributed drinking water, and the European community implements the most stringent pesticide contamination regulations in the world. Municipally treated drinking water in Europe and the United States will therefore require more extensive treatment before distribution than drinking water distributed in Canada.

What are the Guidelines for Canadian Drinking Water Quality?

These Guidelines are comprised of lists of inorganic and organic chemicals (both naturally-occurring and man-made) that should not be present in drinking water in concentrations exceeding the Maximum Acceptable Concentration (MAC), or Interim MAC (IMAC) when a chemical may still be under review. These levels are usually set for health reasons. In addition, the Guideline contains Aesthetic Objectives (AO), which denote compounds that may not have a health impact, but can still be a nuisance.

If one looks closer at the MAC, IMAC, and AO levels for different compounds, it becomes clear that, for some chemicals, even parts per million (milligrams per litre), parts per billion (micrograms per litre) and parts per trillion (nanograms per litre) can cause health and aesthetic problems. For a complete list of drinking water quality guidelines, please consult the Guidelines for Canadian Drinking Water Quality (ISBN 0-660-16295-4, available from book store).

What are the problems with Saskatchewan surface water sources?

Virtually all surface waters (rivers, lakes, dugouts) will contain disease-causing (pathogenic) microorganisms. This is similar to water sources anywhere in the world. Small water volumes and locations close to large numbers of domestic animals can potentially increase these concerns for farm dugout water. Agricultural land and farming practices can potentially contribute to microbial water problems (e.g. by adding nutrients to the water). Removal of microorganisms by filtration and disinfection is therefore required for all surface water used for domestic and drinking water purposes.

Agricultural drainage and a semi-arid climate cause further problems as this results in high levels of dissolved nutrients and organic material in the water (particularly in prairie reservoirs). Nutrients can encourage strong growth of aquatic plants and algae, resulting in further decline in water quality. Organic matter can give water a brown or yellow colour, as well as a distinct taste and odour. Occasionally, the organic material can be toxic. This is the case for many blue-green algae blooms. Some man-made compounds, including pesticides, can also be of concern. Organic compounds make disinfection of the water more difficult. Removal of dissolved organic matter is difficult to achieve with common water treatment systems.

The problems in surface water are caused by particulate organic matter (including microbes) and dissolved organic matter (including taste, odour and coloured compounds). It is quite rare that levels of inorganic compounds (e.g. sodium, sulphate, etc.) are high enough to cause concerns in most Saskatchewan surface water supplies. The exception to this is likely calcium and magnesium levels found in dugouts during winter (under ice conditions, these concentrations often exceed guidelines).

What are the problems in Saskatchewan's ground water sources?

Underground water supplies are called aquifers. A well is considered to be "shallow" when water is pumped from 30 to 40 m (100 feet). When water is pumped from aquifers of more than 40 m depth, the well is called a "deep" well. Since shallow wells are subject to the contamination from land use practices, they are classified as surface water in the United States. Shallow wells may also have similar water problems to those found in deep wells. The most common problems in deep wells are the presence of high levels of inorganic material such as iron, manganese, hardness (magnesium + calcium), sodium, arsenic, total dissolved solids, and sulphates. Shallow wells may also have some unique problems that are less common in either surface waters or deep wells. The most prominent of these are nitrates.

As recommended for surface water, shallow well water should not be consumed for drinking (for humans) without appropriate water treatment. Water from deep wells must be thoroughly tested before a decision to consume without treatment can be made.

Selected guideline values

Selected guideline values for drinking water quality in regard to allowable levels of microorganisms, organic matter and inorganic matter in drinking water is shown in Table 1. The table incorporates information from Canadian Guidelines with some additional information from Saskatchewan's Drinking Water Objectives, the World Health Organization, the European Union and the Safe Drinking Water Foundation. For a complete list of values, please consult the listed information sources.

Table 1: Selected drinking water quality guideline values which should not be exceeded.(Canadian Drinking Water Quality Guideline where only a number is given, SK=Saskatchewan Drinking Water Objective, EU=European Union, WHO=World Health Organization, SDWF=Safe Drinking Water Foundation)

Where can I get my water analyzed?

Commercial and provincial laboratories that are able to analyze the composition of chemicals in drinking water include: Envirotest Laboratories (Saskatoon), BDS Laboratories (Qu'Appelle), Saskatchewan Research Council (Saskatoon), and the Provincial Saskatchewan Health Lab. (Regina).

The bigger picture

The realization that drinking water and food account for the spread of most diseases caused by microorganisms (viruses, bacteria, and protozoa) is prompting world-wide action to prevent this threat to health. Regulations in both Europe and the US will likely be instituted this year to regulate as many as 12 different pathogenic microbes. Canadian guidelines will likely take a similar path in the future. The microbes of concern include some that are already regulated in the US (for example the parasites Giardia and Cryptosporidium) and others like the hepatitis A virus.

Because of microbial and chemical problems in rural surface and ground water supplies in Saskatchewan, most of these water sources cannot be consumed by humans without in-house treatment. Surface water and ground water protection will make the problems less difficult to deal with in-house. Some compounds in the water, such as the dissolved organic matter, make it very difficult to treat. All treatment systems have limitations and will require appropriate operation, maintenance and replacement of parts and material (for example filter media such as activated carbon). When high quality water is required for domestic and drinking water purposes, water testing of both the source water and the tap water is recommended for critical parameters twice per year (summer and winter) to ensure its safety.

Acknowledgements

Strategic support and funding for this publication has been provided by the Canada-Saskatchewan Agri-Food Innovation Fund (AFIF) and WateResearch Corp.

This Fact Sheet is a part of the publication Water Quality Requirements for Saskatchewan's Agri-Food Industry, identifying key water quality needs for each sector. These guidelines were compiled from a variety of references, primarily including extension publications, reports, books and internet sources. Water quality is a vast and complex subject and readers are encouraged to consult with experts and delve into scientific literature for a greater understanding into specific water quality needs.

No Endorsement Given: This report should not be taken as an endorsement by the authors or their agencies of any of the guidelines, products or services mentioned herein.