EM SC 470
Applied Sustainability in Contemporary Culture


graphic depicting the water cycle, including evaporation, condensation, precipitation, ground water storage, and more.
Figure 3.6: The Water Cycle. You probably learned about the water cycle in elementary school. What you may have forgotten is that the amount of water on the earth has been the same for thousands (if not millions) of years and this amount will not change for the foreseeable future. (Link to the text version of Figure 3.6 that opens in a new window.)
Credit: U.S. Geological Survey (public domain)

I'm sure I don't need to tell you that water is essential for life, including humans. The earth is considered a "Goldilocks" planet (not too hot, not too cold) based on the fact that water can exist in a liquid state over much of the planet. All water on earth cycles in and out of this system at different time scales (see the figure above), and has been for millennia. In fact, the water that you used to brush your teeth this morning may have been part of the iceberg that sank the Titanic, ran through ancient Roman aqueducts, or was used to wash the makeup off of Cleopatra's face. This is important to understand, because the water we have now is all of the water we'll ever have. There is no shortage of water, but freshwater is limited. The earth naturally replenishes fresh, clean water, but at a limited rate, and there are many obvious indicators that humans are not using freshwater at a sustainable rate.

The following are a number of facts presented by the World Health Organization in their article "Drinking Water." You are welcome to read through the article, but that is not necessary.

  • In 2015, 71% of the global population (5.2 billion people) used a safely managed drinking-water service – that is, one located on premises, available when needed, and free from contamination.
  • 89% of the global population (6.5 billion people) used at least a basic service. A basic service is an improved drinking-water source within a round trip of 30 minutes to collect water.
  • 844 million people lack even a basic drinking-water service, including 159 million people who are dependent on surface water.
  • Globally, at least 2 billion people use a drinking water source contaminated with faeces.
  • Contaminated water can transmit diseases such diarrhoea, cholera, dysentery, typhoid, and polio. Contaminated drinking water is estimated to cause 502 000 diarrhoeal deaths each year.
  • By 2025, half of the world’s population will be living in water-stressed areas.
  • In low- and middle-income countries, 38% of health care facilities lack an improved water source, 19% do not have improved sanitation, and 35% lack water and soap for handwashing...
  • Contaminated water and poor sanitation are linked to transmission of diseases such as cholera, diarrhoea, dysentery, hepatitis A, typhoid, and polio. Absent, inadequate, or inappropriately managed water and sanitation services expose individuals to preventable health risks...
  • Some 842 000 people are estimated to die each year from diarrhoea as a result of unsafe drinking-water, sanitation, and hand hygiene. Yet diarrhoea is largely preventable, and the deaths of 361 000 children aged under 5 years could be avoided each year if these risk factors were addressed...
  • Diarrhoea is the most widely known disease linked to contaminated food and water but there are other hazards. Almost 240 million people are affected by schistosomiasis – an acute and chronic disease caused by parasitic worms contracted through exposure to infested water...
  • Climate change, increasing water scarcity, population growth, demographic changes and urbanization already pose challenges for water supply systems. By 2025, half of the world’s population will be living in water-stressed areas.

The news is not all bad, though - according to the World Economic Forum (WEF) the United Nations' Millennium Development Goal of "halv(ing) the proportion of the world's population without sustainable access to safe water" was met in 2010. However, the article indicates that while the broad goal was met (global percentage), none of the 48 "least developed" countries met the goal. As usual, there is a deficiency in terms of equity with regards to access to clean water, with "low-income, informal or illegal" populations "usually having less access to improved sources of drinking water than other residents." 

These and other factors combine to make access to water an essential part of the quality of life. The United Nations has declared access to water and sanitation a human right and thus should be provided to all people equitably. The UN realizes that access is a fundamental component of the ability to live one's life and further that "clean drinking water and sanitation are essential to the realization of all human rights" (Credit: United Nations).

Water Scarcity

  • Physical water scarcity "occurs when the demand for water...is higher than the available resource." This is pretty straightforward: this occurs when an area needs more water than it has. This usually occurs in dry areas of the world, including wealthier ones like the southwestern U.S.
  • Economic water scarcity "occurs when human, institutional and financial capital limit access to water even though water in nature is available for human needs." In other words, the water is there and is accessible, but the people are not capable of getting to it. This tends to happen in lower income countries of the world, and areas with social and/or political instability.
    Credit: FAO

Optional Viewing

The following video from FAO has no audio narration, so there is nothing wrong with your speakers/headphones! Note that the data provided are a few years old, but have not changed much. It is important to point out that despite what is indicated in the video above, reducing domestic water use is not the most effective way to reduce total water use. As you will see in the video below, much more water is used as a result of farming and industrial uses worldwide.
Water Scarcity
Click Here for Text Alternative of Water Scarcity Video

It says: Water scarcity occurs when the demand for water from all sectors (agriculture, cities, environment, etc...) is higher than the available resource. Because water has been relatively abundant throughout our existence on earth, we have come to take it for granted. However, we now find our water supplies severely reduced as water scarcity is fast becoming one of the most serious resource issues we face today. The amount of water on our planet is fixed, but very little of it is available for us to use with about 2.5 percent of all water on earth being freshwater and 68.9 percent of the freshwater is locked in glaciers, 30.8 percent in groundwater, and 0.3 percent in lakes and rivers.

Currently, one-third of the world population lives in countries where there isn't enough water or its quality has been compromised. By 2025 this number is expected to rise to two-thirds.

There are two types of water scarcity. One is known as Physical Water Scarcity. This occurs when there is not enough water to meet our needs. Arid regions are generally associated with physical water scarcity. Physical water scarcity occurs in: the western United States, northern Africa, Saudi Arabia, eastern Australia, and areas of India and northern China. More areas are rapidly approaching physical water scarcity. Africa, Asia and the Pacific, and the Near East use over 75 percent of their water for agriculture. The other type of water scarcity is known as Economic Water Scarcity. This occurs when human, institutional and financial capital limit access to water even though water in nature is available for human needs. Economic water scarcity occurs in central and northern South America, Middle Africa, and in and around India. Poor households in developing countries spend higher portions of their income on water than families in industrialized nations.

You may think water issues are somebody else's problem. But in a few years, it will be yours too. Follow a few easy steps to do your part in maintaining this precious resource. Don't throw your cooking water down the drain. Close the tap when brushing your teeth. Don't buy unnecessary goods, as everything produced uses water.

Credit: FAO

Here are some things to keep in mind about water scarcity, according to the United Nations:

Water scarcity already affects every continent. Around 1.2 billion people, or almost one-fifth of the world's population, live in areas of physical scarcity, and 500 million people are approaching this situation. Another 1.6 billion people, or almost one quarter of the world's population, face economic water shortage (where countries lack the necessary infrastructure to take water from rivers and aquifers).
Water scarcity is among the main problems to be faced by many societies and the World in the XXIst century. Water use has been growing at more than twice the rate of population increase in the last century, and, although there is no global water scarcity as such, an increasing number of regions are chronically short of water.
Water scarcity is both a natural and a human-made phenomenon. There is enough freshwater on the planet for seven billion people but it is distributed unevenly and too much of it is wasted, polluted and unsustainably managed...
  • Around 700 million people in 43 countries suffer today from water scarcity.
  • By 2025, 1.8 billion people will be living in countries or regions with absolute water scarcity, and two-thirds of the world's population could be living under water stressed conditions.
  • With the existing climate change scenario, almost half the world's population will be living in areas of high water stress by 2030, including between 75 million and 250 million people in Africa. In addition, water scarcity in some arid and semi-arid places will displace between 24 million and 700 million people.
  • Sub-Saharan Africa has the largest number of water-stressed countries of any region
Graphic depicting water scarcity across the world.
Figure 3.7: Global water scarcity. Note that scarcity exists on all continents, including in some wealthier areas of the world.
Click for a description of the graphic.
  • Economic water scarcity: Sub-Saharan Africa, parts of northwestern South America, northern India and some of southeast Asia
  • Physical water scarcity: Northern China, parts of the Middle East, southeastern Australia, southwest U.S.
  • Approaching physical water scarcity: Central Mexico and parts of Texas, South Africa, most of the Middle East, some in northern China.
  • Little or no water scarcity: Most of the rest of the world, except for Alaska, Greenland, Siberian Russia, and Central Australia, which had no data.

Considering that about 97% of the water in the world is salt water, one of the ways that scarcity can be overcome is through desalination. This is being done all over the world, but current desalination technology requires an immense amount of energy, can impact local environments in a variety of ways, and is quite expensive. Desalination is probably necessary to satisfy the world's energy needs (and likely increasingly so), particularly in arid areas of the world. But as succinctly stated by Scientific American: "Due to its high cost, energy intensiveness and overall ecological footprint, most environmental advocates view desalinization...as a last resort for providing fresh water to needy populations."

Water Use

It is a common misconception that household water use (taking showers, washing dishes, etc.) is the primary driver of water use in the world, but only about 8% of global freshwater consumption is from domestic uses. Most - about 70% - is used for agriculture, and over 20% is used for industrial purposes (e.g., manufacturing, energy generation).

It turns out that U.S. water consumption follows a similar pattern. The chart below shows the percent of consumption different sectors of use are responsible for. Some interesting things to note:

  • Thermoelectric cooling is the single biggest user of total water in the U.S. (about 40%). (Keep in mind that about 50 billion gallons of salt water are used for thermoelectric power, so irrigation is the biggest single freshwater user in the U.S.).
  • Irrigation is responsible for about 38% of annual water use, but about 42% of freshwater used.
  • Domestic water use accounts for about 2% of the total.
Pie Chart of estimated water use in the U.S. in 2015.
Figure 3.8: Summary of Estimated Water Use in the United States in 2015.
Click for a text description
2015 Withdrawals by Category, in Million Gallons per Day
Public Supply 39,000
Self-Supplied Domestic 3,260
Irrigation 118,000
Livestock 2,000
Aquaculture 7,550
Self-supplied Industrial 14,800
Mining 4,000
Thermoelectric Power 133,000

Note: Values do not sum to 322,000 Mgal/d because of independent rounding.

  • Total withdrawals were 322,000 million gallons per day (355 billion gallons per day).
  • Thermoelectric power, irrigation, and public supply account for 90 percent of total withdrawals.
  • Withdrawals declined since 2010 in all categories except irrigation.
  • Freshwater withdrawals were about 88% of the total.
  • Surface water supplied 78 % of all withdrawals
Credit: U.S. Geological Survey. Public Domain.

Keep in mind that not all water use is consumptive. For example, almost all water used in thermoelectric cooling is used for just that - cooling. Most of it ends up either as steam or as warm(er) water downstream of the power plant. Most of the water used for irrigation is consumptive (62%, according to the USGS), in that it ends up being incorporated into the crops. When water moves from one part of the water cycle to another, it can be days (water lasts about 9 days on average in the atmosphere) to thousands of years (e.g., in the ocean) before it moves to another part of the cycle. (Refer to this description of residence time from the National Center for Environmental Research.)

Water Footprint

Given that most water in the world is used to grow crops and generate electricity, it follows that most of the water we use is used indirectly. Every time you use something that must be grown as a crop (food, cotton, wood, etc.) or use electricity (assuming it is from a power plant), you contribute to water use. This "hidden" water of everyday products and processes is considered the water footprint. The Water Footprint Network defines water footprint as "the amount of water used to produce each of the goods and services we use" (Credit: Water Footprint Network).

A water footprint - like an ecological footprint - can be calculated for individual products, individual people, or groups of people (communities, cities, countries, etc.). The folks at the Water Footprint Network provide a lot of information about water footprints. Feel free to take a look at the Water Footprint Network's product gallery to see the (often surprising) water footprint of many common items.