What is the Percentage of Drinkable Water on Earth?


Answering the question about the percentage of drinkable water on earth by providing data found on related NGO, scientific research, and governmental websites. Discussing the hydrologic cycle and the different sources of clean water throughout the earth. Address clean water scarcity problems among impoverished regions.


Updated: July 5, 2023
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Jeremiah Zac
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There are 326 million cubic miles of endless blue sea occupying the expanse between our seven continents, making up 70% of the earth’s surface (Bureau of Reclamation, 2017).

With merely 5% of the ocean floor having been discovered and mapped and the deepest part reaching almost 7 miles, water seems to be as abundant as it is ominous.

Yet, if consumed, it wouldn’t take much of the mineral-rich ocean to dehydrate a human being. The amount of sodium in seawater is much more concentrated than the body can safely process, requiring more water as salt is consumed. Eventually, death would come due to dehydration without ever having the thirst quenched (Ocean Service).

Of the waters occupying 70% of the earth’s surface, only 3% is considered freshwater. And most of this freshwater reserve is inaccessible to humans — locked up in polar ice caps or stored too far underneath the earth’s surface to be extracted. Furthermore, much of the freshwater that is accessible has become highly polluted.

This leaves us with roughly 0.4% of the earth’s usable and drinkable water to be shared among the 8 billion inhabitants (World Atlas, 2018).



How Much Water is On Earth?


Image

  • Oceans 97.2%
  • Ice Caps/Glaciers 2.0%
  • Groundwater 0.62%
  • Freshwater Lakes 0.009%
  • Inland Seas/Salt Lakes 0.008%
  • Atmosphere 0.001%
  • Rivers 0.0001%



And still, much of this 0.4% is hard to get to. Most of it flows through underground aquifers accessed by wells; the rest are found in rivers and streams, which we refer to as surface water. Much of the global population is hard-stricken, having access to such a small percentage of freshwater on the earth’s surface (Perlman, 2016).


global-water-volume-fresh-large

The United States Geological Survey provides a visual illustration (represented in spheres) as to the amount of available water in comparison to the size of the earth.

The largest sphere represents all of the water on earth (oceans, ice caps, lakes, rivers, groundwater) and has a volume of 332,500,000 cubic miles.

The second-largest sphere, with a volume of 2,551,100 cubic miles, represents the earth’s freshwater supply in liquid form.  99% of the liquid freshwater is groundwater, most of which is far too deep to be accessible.

The remainder of the earth’s freshwater exists in lakes and rivers, represented by the tiniest sphere, with a volume of 22,339 cubic miles (Perlman, 2016).


We use
0 billion gallons
of surface water per day
and
0 billion gallons
of groundwater per day

Since surface water is easier to reach, it’s become the most common way humans can access clean water. Globally, we use about 321 billion gallons of surface water and about 77 billion gallons of groundwater daily. Contamination of these water supplies is a problem that further limits availability (Groundwater Association, 2012).



Surface Water


Surface water is any body of water on the earth’s surface: lakes, rivers, streams, and reservoirs. 80% of the world’s daily water usage comes from surface water, making up most of the water used for irrigation and public supply. Oceans are the world’s largest source of surface water and makeup 97% of it, but due to its high salinity, it is unusable for humans (Postel, 2010).

The earth’s surface waters travel through a complex network of rivers and streams. Rivers can obtain their water from two sources: base flow and runoff. Base flow is when the river collects water from water-saturated areas in the ground, adding to its volume. Runoff is when the force of gravity naturally pulls water downhill from higher to lower altitudes. They usually start as small creeks in the mountains and then gradually merge with larger streams as they flow downward, eventually forming large rivers which empty out into the ocean.


Groundwater


Groundwater is the water beneath the earth’s surface that travels through porous rock known as aquifers. 98% of the earth’s freshwater is groundwater, and it is about 60 times more plentiful than surface water.

Groundwater is accessed via a drilled well. The pressure within an aquifer can vary, and in some cases, it can be high enough to push groundwater up to the surface once a well has been dug. (Groundwater Association, 2012).


The Hydrologic Cycle


Water takes the form of liquid, gas, and solid and cycles through these in what is known as the earth’s hydrologic cycle. When water evaporates, liquid molecules become gas molecules as they rise through the atmosphere. Condensation begins when the moisture from these gas molecules becomes so great that they fall back to earth as precipitation. Because evaporation, condensation, and precipitation have essentially “distilled” the water, it is considered clean before it hits the ground. When the precipitation hits the ground, it collects into aquifers, rivers, or lakes, ready to be used again. Glaciers and icecaps cover 10% of the world's mass and exist primarily in Greenland and Antarctica. They are the storehouses for the world’s freshwater.

Water Conflicts Around the World


militant soldiers

There are 263 rivers and countless aquifers worldwide, crossing or demarcating geopolitical boundaries. The Atlas of International Freshwater Agreement states that 90 percent of the world’s countries share these water sources with at least one or two other governing bodies. The atrocities in Darfur are an example of conflict resulting from clean water shortages.

• Violence erupted in 1992 over a dispute between Uzbekistan and Turkmenistan regarding the contested Tyuyamuyun reservoir. It remains a highly disputed water source in the region today (Factbook).

• In 2010, dozens of people were killed in Pakistan’s tribal region due to a water dispute which lasted over two weeks. According to a senior government official in the Kurram district, which borders Afghanistan, the Mangal tribe stopped water irrigation on lands belonging to the Tori tribe. In total, 116 people were killed, and 165 were injured (CNN, 2010).

• Four farmers were hacked to death in northeast Tanzania over the disputed Pangani River Basin in 2013 (Factbook).

• In 2016, 18 people were killed, and 200 more were injured when the Indian Army clashed with economic protestors surrounding the highly-contested Munak canal, a water source that supplies New Dehli with three-fifths of its freshwater supply (Factbook).

• The drought-stricken conditions of major parts of Somalia often force herders to sell more of their livestock than they can afford to make a living with. This lack of economic stability fuels recruitment appeals with militant groups such as Al Shabaab, which provide cash incentives and other benefits to their soldiers. Other illicit activities, such as pirating and livestock raiding, are seen as reasonable alternatives to the declining stability of animal herding (Factbook).


Change is Needed


Water is finite. The amount of water circulating through the earth’s hydrologic cycle is the same amount that has been there since the earth’s beginning, not a drop more or less. What has changed is the number of people living on Earth, thus, the amount of drinkable water required for human sustenance. The United Nations reports that in the last century alone, water consumption has grown at more than twice the rate of population increase.

70% of the earth is covered in water, yet only 3% of it is fresh. Of that 3%, 2.6 of it is locked away in glaciers and polar ice caps. That leaves us with 0.4% of the earth’s water, in the form of rivers and underground aquifers, to try to utilize for our consumption and societal development. It is no wonder that in developing regions where clean water sources cross national boundaries, it often finds itself in conflict among those trying to secure a means to a healthy living.

With humans comprising 60% water, our natural instinct might be to fight for it. But by collaborating to find ways to access the untapped groundwater beneath us, helping to conserve clean water use, and preventing further pollution of our clean water sources, it is possible for all peoples to have access to clean water.


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References

Bureau of Reclamation. (2017, April 10). Water Facts - Worldwide Water. Retrieved from https://www.usbr.gov/mp/arwec/water-facts-ww-water-sup.html

CNN. (2010, September). Water conflict in Pakistan's tribal region leaves dozens dead. Retrieved from http://www.cnn.com/2010/WORLD/meast/09/19/pakistan.water.dispute/

Factbook. (n.d.). Mapping environmental conflicts and cooperation. Retrieved from https://factbook.ecc-platform.org/

Groundwater Association. (2012, September). Information on Earth's water - National Groundwater Association. Retrieved from http://www.ngwa.org/Fundamentals/teachers/Pages/information-on-earth-water.aspx

National Geographic. (2017, January 27). Competing for Clean Water Has Led to a Crisis. Retrieved from https://www.nationalgeographic.com/environment/freshwater/freshwater-crisis/

Ocean Service. (n.d.). Can humans drink seawater? Retrieved from https://oceanservice.noaa.gov/facts/drinksw.html

Perlman, H. (2016, December 2). Where is Earth's water? USGS Water-Science School. Retrieved from https://water.usgs.gov/edu/earthwherewater.html

Perlman, H. (2016, December 2). How Much Water is on and in the Earth. Retrieved from https://water.usgs.gov/edu/gallery/global-water-volume.html

Postel, S. (2010, June). How Much Longer Until We Run Out of Enough Drinkable Water? Retrieved from https://www.alternet.org/story/147334/how_much_longer_until_we_run_out_of_enough_drinkable_water

Shahan, Z. (2017, October 24). How Much Clean Water is Available for Human Use? Retrieved from https://insteading.com/blog/clean-water-human/

United Nations. (2007). Water scarcity. Retrieved from http://www.un.org/waterforlifedecade/scarcity.shtml

World Atlas. (2018, February 14). What Percentage of the Earth's Water Is Drinkable? Retrieved from https://www.worldatlas.com/articles/what-percentage-of-the-earth-s-water-is-drinkable.html

I'm Jeremiah, the owner of World Water Reserve. I'm a writer and researcher with a particular interest in sustainability and rural living, water scarcity, and innovative water purification methods. I utilize my multimedia and communication experience in the NGO and humanitarian fields to bring light to important topics. My passion is to educate others on the reality of the global water crisis and on ways to sustain themselves and their families in the midst of it.
Jeremiah Zac