Earth

There is a reason the Earth looks so blue, 70% of the Earth’s surface is covered in water. Water is an essential part of life for all creatures on the planet, from the tiniest bacteria to the tallest tree. None of us could survive long without it.

You have probably heard water referred to as H2O. This is because water is made up of three atoms - two hydrogen atoms (H2) and one oxygen atom (O).

Water is found in three different forms: as a liquid, a solid (ice), and a gas (water vapour). As a liquid we bathe in and drink it, as a solid it keeps our drinks cool, as a gas it blankets the Earth keeping it warm.

Next: How Much Is There?

Adapted from Pollution Probe's Drinking Water Primer

Distribution of Water on Earth

About 70% of the Earths surface is covered by water, so you might think that with all this water, there ought to be plenty to go around for everyone. But unfortunately that isn’t the case.

Of all the water on Earth, 97% of it is salt water and is not suitable for drinking. While the remaining 3% is fresh water, 79% of this freshwater is frozen in glaciers and ice caps and 20% is under the ground. The 1% left is found in the atmosphere, in lakes, rivers, streams and wetlands; this is the water we all depend on for drinking, washing, gardening and recreation.

Showing how water moves through the environment, can help illustrate the importance of protecting our water resources. The first thing to know is that the amount of water on the planet has been roughly constant since the Earth was formed more than four and a half billion years ago. The water you drink today could be composed of the same water molecules that Canada’s first Prime Minister, Sir John A. MacDonald, drank in the mid-19th century, or even the same molecules drank by a prehistoric animal many millions of years ago.

Water is vital - not just because it keeps us alive, it also ensures the health of ecosystems and economies, and plays an important role in many cultures.

What is an Ecosystem?Aquatic Ecosystem

An ecosystem is a community made up of animals, plants, and micro-organisms, together with the environment where they live. Members of the community depend on each other and their environment for food and shelter. Ecosystems have four main components: air, water, land and living creatures. Every ecosystem on Earth depends on water, of varying amounts, for its survival. Human beings rely on aquatic ecosystems for many things. They provide the water we use for drinking, bathing, growing food, cooking, transportation and recreation.

The water we rely on is the same water that plants and animals need to survive. This is one of the reasons why it is important for people to take great care with the water they use. If either water quality is degraded or water quantity altered, this can have a serious impact on an ecosystem. Everything is connected; eventually our lack of care will affect us too.

Conservation AreasIn Canada, water is managed by the federal, provincial, and municipal governments, and in some cases, by Aboriginal governments under self-government agreements. For the most part, waters that lie within a province's boundaries are managed by that province. The waters flowing in the national parks, First Nation reserves, and other federal lands are the responsibility of the federal government.

A watershed is the area of land that catches rain and snow which drains or seeps into a common water body such as a marsh, stream, river, or lake.

Watersheds include all water and water-dependent land features, such as wetlands, forests, towns, humans and other living things. They are of differing shapes and sizes, and cut across municipalities, provinces and countries. Watersheds are separated from one another by a land ridge or divide.