Where does Water come from?

Learn about how water is found on Earth….

There are three different forms of water that are found on Earth. Water can be found in a liquid form in oceans, rivers, lakes, and rain. It can be found in solid form in ice and snow. Finally, water can be found as a gas (water vapour) in the atmosphere.

The main sources of water on Earth are:

  • Oceans
  • Lakes
  • Rivers
  • Glaciers and Icecaps
  • Aquifers
  • Ponds
  • Springs
  • Rainwater

Surface Water

 

Oceans

Oceans are the largest sources of water on the planet. There are five oceans in the world:

  • Arctic Ocean
  • Indian Ocean
  • Atlantic Ocean
  • Pacific Ocean
  • Southern Ocean

They contain 97% of all Earth’s water. However, ocean water is not suitable for humans to drink in its raw form. It contains high salt levels and other impurities that make it unsuitable for household use. Salt-water can be purified so that it can be used as drinking water, this process is called desalination. Desalination costs a large sum of money and requires high levels of energy so is not widely used.

Lakes

It is estimated that there are 117 million lakes throughout the world. Lakes are classified into two categories: salt-water lakes and freshwater lakes. The main use of lake water is in the fishing industry, rather than being used for drinking water.

Rivers

Rivers are natural pathways through which water flows towards another river or larger body of water. Rivers are a critical source of water for many reasons:

  • Source of food
  • Mode of travel
  • Hydropower sources
  • Farming

Ponds

Ponds are shallow water sources and are usually smaller than a lake. Ponds can be naturally formed but some are man-made. Water found in ponds is often used to support agriculture, fishing industry, and in rehabilitation of damaged land. They can also be hubs of biodiversity in the areas that they are found.

Rainwater

Rainwater is a seasonal source of water. It is also the cheapest naturally occurring water source. Rainwater is collected in water tanks and dams during rainier seasons for use in dry seasons. Rainwater is used for household needs, farming, replenishing ponds, and hydro-power generation.

Groundwater

Aquifers

Aquifers are sources of water found below the surface of the Earth. They are an underground layer of water-bearing rock. These rocks are permeable, meaning that liquids and gases can pass through them. Groundwater is the water contained in the aquifers.

They are replenished/recharged by rainfall that percolates through the soil to the water table, and by water seeping from streams, as well as other bodies of surface water, such as lakes and wetlands.

 

An estimated 30% of the world’s liquid water is found below ground. Water in underground aquifer may come to surface through natural springs.

 

In some cases, the water is pumped to the surface through specialised equipment. Aquifers are very important water sources, especially in arid areas. The cost extracting this water from aquifers is often achievable. Some aquifers host saline water and must be desalinated before being put into use.

Springs

Springs are natural freshwater sources found on the Earth’s surface. They get their water from underground streams or aquifers. Springs can produce hot water in the form of geysers while others can produce cold water. Spring water is often used in the commercial production of drinking water.