Introduction to water quality


We tend to think of water in terms of a particular purpose: is the quality of the water good enough for the use we want to make of it? Water fit for one use may be unfit for another. We may, for instance, trust the quality of lake water enough to swim in it, but not enough to drink it. Along the same lines, drinking water can be used for irrigation, but water used for irrigation may not meet drinking water standards. It is the quality of the water which determines its uses.

Scientists, on the other hand, are interested in other aspects of water quality. To them quality is determined by the kinds and amounts of substances dissolved and suspended in the water and what those substances do to inhabitants of the ecosystem. It is the concentrations of these substances that determine the water quality and its suitability for particular purposes.

Drinking water, for example, is regulated by guidelines stringent enough to protect human health. Lack of such guidelines can lead to a variety of health problems.

Water is the lifeblood of the environment, essential to the survival of all living things -- plant, animal and human -- and we must do everything possible to maintain its quality for today and the future.

Canada: a water paradise?

Here in Canada we are fortunate. We have extensive supplies of water. Our pristine rivers and lakes filled explorers and settlers with a sense of majesty and awe. Today, they continue to impress Canadians and visitors alike. Yet under the pressures of human development, many of these waters are losing their unspoiled quality.

It is no wonder. We dispose of human wastes, animal wastes and chemical substances into the environment at such a rate that even some of the largest lakes and river systems -- the Great Lakes and the St. Lawrence River, for example -- are having serious difficulty cleansing themselves and sustaining life.

Factors Influencing Water Quality

The water of even the healthiest rivers and lakes is not absolutely pure. All water (even if it is distilled) contains many naturally occurring substances -- mainly bicarbonates, sulphates, sodium, chlorides, calcium, magnesium, and potassium.

Total dissolved solids in selected Canadian rivers

Many factors affect water quality. Substances present in the air affect rainfall. Dust, volcanic gases, and natural gases in the air, such as carbon dioxide, oxygen, and nitrogen, are all dissolved or entrapped in rain. When other substances such as sulphur dioxide, toxic chemicals, or lead are in the air, they are also collected in the rain as it falls to the ground.

Rain reaches the earth's surface and, as runoff, flows over and through the soil and rocks, dissolving and picking up other substances. For instance, if the soils contain high amounts of soluble substances, such as limestone, the runoff will have high concentrations of calcium carbonate. Where the water flows over rocks high in metals, such as ore bodies, it will dissolve those metals. In the Canadian Shield, there are large areas with little soil and few soluble minerals. Consequently, the rivers and lakes in these areas have very low concentrations of dissolved substances.

Another factor influencing water quality is the runoff from urban areas. It will collect debris littering the streets and take it to the receiving stream or water body. Urban runoff worsens the water quality in rivers and lakes by increasing the concentrations of such substances as nutrients (phosphorus and nitrogen), sediments, animal wastes (fecal coliform and pathogens), petroleum products, and road salts.

Industrial, farming, mining, and forestry activities also significantly affect the quality of Canadian rivers, lakes, and groundwater. For example, farming can increase the concentration of nutrients, pesticides, and suspended sediments. Industrial activities can increase concentrations of metals and toxic chemicals, add suspended sediment, increase temperature, and lower dissolved oxygen in the water. Each of these effects can have a negative impact on the aquatic ecosystem and/or make water unsuitable for established or potential uses.

How does water clean itself?

Water is purified in large part by the routine actions of living organisms. Energy from sunlight drives the process of photosynthesis in aquatic plants, which produces oxygen to break down some of the organic material such as plant and animal waste. This decomposition produces the carbon dioxide, nutrients and other substances needed by plants and animals living in the water. The purification cycle continues when these plants and animals die and the bacteria decompose them, providing new generations of organisms with nourishment.

Unfortunately, there are many toxic substances which are affected only slowly, or not at all, by this and other processes. These are called persistent and are of great environmental concern.

Human Health and Water Quality

In Canada we are lucky to have plentiful supplies of good drinking water sources. Water-related illnesses -- typhoid fever, cholera, dysentery -- are almost unknown in this country today. Waste and wastewater treatment, the development and enforcement of drinking water guidelines, public health practices and education -- all have resulted in a decrease in water related illnesses in Canada. Developing nations are less fortunate: 80% of their diseases are water-related.

The price Canadians must pay to prevent water-borne disease is constant vigilance against bacterial contamination. Periodic beach closures and local epidemics are evidence that the battle is never won. These problems underscore the need for maintaining strict control over water quality and for improving water and wastewater treatment.

Of serious concern today are the toxic chemicals that enter our waters from many different sources, including industry, agriculture and the home. Little is known about the effects of these toxic substances on human health; often the effects do not become noticeable for long periods of time, and it is difficult to distinguish them from the effects of other factors that impact on our day-to-day life (e.g., nutrition, stress, air quality). Much more remains to be done to control toxic chemical pollution. Meanwhile, we can all contribute to the prevention of water pollution by not abusing the water or the land.

Water Quality Facts

  • Approximately 57% of Canadians are served by wastewater treatment plants, compared with 74% of Americans, 86.5% of Germans, and 99% of Swedes.
  • In developing nations, 80% of diseases are water-related.
  • Of all Canadians, 26% rely on groundwater for domestic use.
  • One drop of oil can render up to 25 litres of water unfit for drinking.
  • One gram of 2,4-D (a common household herbicide) can contaminate ten million litres of drinking water.
  • One gram of PCBs can make up to one billion litres of water unsuitable for freshwater aquatic life.
  • One gram of lead in 20 000 litres of water makes it unfit for drinking. Older homes often contain plumbing made of lead or soldered in lead, which can then leach into water.
  • The nitrates in fertilizers promote excessive growth of algae and larger aquatic plants, causing offensive algal blooms and driving out sport fish.
  • Methane gas can often be seen bubbling up from the bottom of ponds; it is produced by the decomposition of dead plants and animals in the mud.
  • Calcium and magnesium -- both essential elements for man - account for most water hardness. Death rates for certain types of cardiovascular disease have been found to be higher in soft water areas than in hard water areas in many parts of the world.
  • Copper is another essential element -- for optimal absorption and metabolism of iron and for bone formation -- and fairly common in natural water. More than one milligram per litre may make water unpalatable.

What you can do

In the face of this planet's overwhelming environmental problems, each individual effort to protect water quality is vital. Together, individual actions can and do make a difference to water quality and the environment as a whole. You can start by taking the following actions:

Avoid hazardous household products

Most proprietary household chemicals are safe to use and are environmentally friendly, when used according to the directions on the package. However, some have a harmful cumulative effect on the environment when they are over-used or incorrectly disposed of.

  • Check the label for hazard warnings. The symbols used on hazardous household chemical products are shown below:

  • Symbols used on hazardous household chemical products.

The warning symbols are based on shape: the more corners a symbol has, the greater the risk. Read the label to find out how to use the product safely and what precautions to take.

  • Buy only those environmentally hazardous products you really need, and buy them in quantities you will be able to completely use up, so that you will not have to worry about disposing of the leftovers later.
  • Use "environmentally friendly" products now available in your supermarket and drugstore.
  • The federal government endorses products that are environmentally friendly. Look for the Environmental Choice EcoLogo. Products bearing this label have been tested and certified by the Canadian Standards Association. Each dove represents a sector of society - consumers, industry, and government - linked together to improve and protect the environment. The logo identifies the products that maximize energy efficiency and the use of recycled or recyclable materials and minimize the use of environmentally hazardous substances. Consumers can make informed choices.

Don't misuse the sewage system

Don't throw waste down the drain just because it's convenient. Toxic household products can damage the environment and return to us through water and food.

  • toss items such as dental floss, hair, disposable diapers and plastic tampon holders into the wastebasket, not the toilet - these items create many problems at the sewage treatment plant;
  • always use up completely (or pass on for other people to use) the unused contents of oven, toilet bowl and sink drain cleaners; carpet and furniture cleaners and polishes; bleaches, rust removers and solvents; paints and glue; and most other acid and alkali products;
  • save food scraps (except dairy and meat) and compost them; don't dump them down the drain;
  • choose latex (water-based) paint instead of oil-based and use it up instead of storing or dumping it.

Don't use pesticides or other hazardous materials in your garden

Adopt alternative pest control methods, such as:

  • hand pulling weeds
  • snipping and discarding infested leaves
  • dislodging insects with insecticidal soap or a water hose
  • practising companion planting
  • setting ant and roach traps instead of using chemical sprays
  • applying a natural insecticide such as diatomaceous earth, available in garden centres
  • fertilize with natural materials such as bone meal or peat

Don't dump hazardous products into storm drains

Storm drains empty directly into nearby streams in many areas. The contents of storm sewers are generally not processed at sewage treatment facilities and can therefore do immediate harm to fish and wildlife. Beach closures are a typical example of storm water pollution in many communities.

  • DON'T pour oils, paint compounds, solvents and other products into storm sewers, onto the street, or into your driveway
  • DO take them to local recycling or disposal facilities. Some communities even organize hazardous waste disposal days; contact local health and environment officers or waste disposal companies for details. If nothing comparable exists in your community, introduce and promote the idea
  • DO contact your local Fire Department, which will normally accept unwanted remainders of barbecue starter fluids, lighter fluids, gasoline and furnace oils.

Don't forget about water quality - even when you're having fun

  • power boats can pollute the water through gasoline leaks and spills. Consider using a sailboat, rowboat, canoe or kayak. If you use a powerboat, keep the engine in good repair to avoid leaking oil, gasoline and solvents;
  • if you are a cottage owner, make sure you have a proper sewage disposal system;
  • while camping, always bury biodegradable waste at least 60 meters (200 feet) from any water source. Use only biodegradable soaps, and take your non-biodegradable garbage with you for proper disposal.

Take further action

There is more you can do! For instance:

  • read up on environmental issues
  • be willing to change your attitudes, behaviour and expectations
  • write away for more information on environmentally-friendly products and methods
  • urge and support federal, provincial and municipal action on environmental issues
  • join and support local and national environmental groups that work to solve environmental problems; they are always in need of more volunteers and different talents
  • boycott environmentally harmful products and let the stores know why
  • attend public hearings, participate in advisory boards, address review committees, request information - as a citizen, you have these rights and should seize these opportunities
  • inform your friends and educate your children
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