Water is a precious resource. We can’t live without it. If you look at a map of the world you will see that much of our planet is covered in water. Our oceans are not the only source of water. Water is also present under the ground and as vapor in the air. Clouds formed by this vapor ensure that water falls back down to Earth as rain, sleet, snow or hail.
Oceans of water
There is a lot of water all around us but most of this is not freshwater. Ocean water has too much salt in it for us to drink. Much of the water that falls back to Earth in one form or another becomes runoff. It travels some distance over land before making its way back to one of Earth’s oceans. As it travels over land, the water picks up salts and minerals from the rocks and soil and washes them into the ocean. The deposits have built up over many years. That is why ocean water is so salty.
Approximately 97% of Earth’s water is salt water. That leaves only about 3% that is freshwater for meeting the needs of people, plants and animals.
Only about a third of our freshwater is available for us to use. The rest is frozen solid in glaciers, in the snow on high mountaintops and in the polar ice caps.
The freshwater we use comes from surface water and groundwater. Surface water is water we can see in ponds, rivers, lakes and streams. Groundwater is water that seeps down into the ground and collects in the spaces between rocks and soil underground.
It is important to protect our water supplies from pollution. Once the water becomes polluted, it can be difficult or even impossible to clean.
Chemicals, like cleaning supplies, paints and other toxins, can seep into the ground and make the water unusable. People must dispose of their waste products appropriately so we will have plenty of freshwater in the future.
Streams, rivers and lakes provide habitat for certain types of aquatic plants, fish, insects and birds. Some of these organisms need very pure freshwater.
Almost all organisms on Earth today contain at least 50% water in their bodies. Living things use water to transport nutrients, hormones and oxygen to their cells, cleanse waste from their systems and cool their bodies.