Water

Figure 3.14: 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 that this amount will not change for the foreseeable future. (Link to text version of Figure 3.10 that opens in a new window.)

Credit: U.S. Geological Survey (public domain)

It is a widely known fact that people can survive much longer without food than without water. Under optimal conditions, humans can go around a week, maybe a bit more, without water, whereas it is possible to go more than a month without eating food. But when water sustainability is being discussed, it is rare that death from lack of drinking water is the concern. A more likely cause of death (or, otherwise, a reduction in quality of life) is lack of clean water, and the water-borne diseases like diarrhea and cholera that result. Lack of access to water will likely be a very important problem in the future, though it also poses a threat right now.

The following is some of the more important (and startling) information from the readings above:

• Globally, at least 1.7 billion people use a drinking water source contaminated with feces
• Contaminated water and poor sanitation are linked to transmission of diseases such as cholera, diarrhea, dysentery, hepatitis A, typhoid, and polio.
• Some 1 million people are estimated to die each year from diarrhea as a result of unsafe drinking-water, sanitation, and hand hygiene. Yet diarrhea is largely preventable, and the deaths of 395,000 children aged under 5 years could be avoided each year if these risk factors were addressed.
• Where water is not readily available, people may decide handwashing is not a priority, thereby adding to the likelihood of diarrhea and other diseases.
• Climate change, increasing water scarcity, population growth, demographic changes and urbanization already pose challenges for water supply systems. Over 2 billion people live in water-stressed countries.

While this paints a bleak picture, some progress has been made in the global fight for access to clean water, as evidenced by the fact that the UN's Millennium Development Goal (MDG) on drinking water has been met. The MDG was to "halve the proportion of the world's population without sustainable access to safe water." This goal 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." The consequences are dire, as around 1 million people are estimated to die each year from diarrhea alone, including nearly 400,000 children under the age of 5. And over a quarter of a billion people had to be treated for schistosomiasis, which is a painful chronic disease also caused by water contamination. The worst part is that this is mostly preventable!

These and other factors combine to make access to water an essential part of 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" (Source: United Nations).

All of this is reflected in the World Economic Forum's (WEF) Global Risk Report 2016, which ranked water as the third highest global risk in terms of "impact." (The 2019 report lists it as number 4 in terms of impact.) Note that the WEF did not rank water crisis on a large scale as highly likely relative to other things, including extreme weather, but that if it does occur, it will be very impactful. This speaks to the importance of access to water.

Good to Know - Sustainable Development Goals

The United Nations declared its Millennium Development Goals in 2000. They focused on 8 themes, each with many practical steps listed as ways to achieve the goals:

• Eradicate extreme poverty and hunger
• Achieve universal primary education
• Promote gender equality and empower women
• Reduce child mortality
• Improve maternal health
• Combat HIV/AIDS, Malaria, and other diseases
• Ensure environmental sustainability
• Develop a global partnership for development

Actions were to be taken for a period of 15 years and assessed every year along the way. This period concluded in 2014, and in 2015 the UN published the final report assessing the progress toward the goals. You can view The Millennium Development Goals Report. This is optional reading but will give you a very good feel for a lot of the development activities undertaken by the UN.

These have been replaced by the Sustainable Development Goals. These were adopted by the UN in 2015 as part of the 2030 Agenda for Sustainable Development. According to the UN, this agenda "provides a shared blueprint for peace and prosperity for people and the planet, now and into the future. At its heart are the 17 Sustainable Development Goals (SDGs), which are an urgent call for action by all countries - developed and developing - in a global partnership. They recognize that ending poverty and other deprivations must go hand-in-hand with strategies that improve health and education, reduce inequality, and spur economic growth – all while tackling climate change and working to preserve our oceans and forests."

The SDGs are quite well known, and many public and private entities (and educational institutions) are using them to provide a framework for applying sustainability. The 17 Sustainable Development Goals are as follows. You will probably note that almost all of these are addressed to some extent in this course!

• No Poverty
• Zero Hunger
• Good Health and Well-Being
• Quality Education
• Gender Equality
• Clean Water and Sanitation
• Affordable and Clean Energy
• Decent Work and Economic Strength
• Industry, Innovation, and Infrastructure
• Reduced Inequalities
• Sustainable Cities and Communities
• Responsible Consumption and Production
• Climate Action
• Life Below Water
• Life on Land
• Peace, Justice, and Strong Institutions
• Partnerships for the Goals

Figure 3.15: The Sustainable Development Goals

Credit: United Nations Department of Economic and Social Affairs

Water Scarcity and Sectoral Use

The Food and Agriculture Organization of the United Nations (FAO) indicates that its goal is to "achieve food security for all and make sure that people have regular access to enough high-quality food to lead active, healthy lives" (Source: FAO). They are widely regarded as a leading international organization in the movement to alleviate malnutrition and food poverty across the world, particularly in impoverished areas of the world. In the video below (viewing is optional), they provide an introduction to the concepts of physical water scarcity and economic water scarcity and provide some data about these two phenomena.

• 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.
  Source: FAO

Suggested Reading

You are welcome to read from the beginning through the "Water stress versus water scarcity" section on the United Nation's "International Decade for Action 'WATER FOR LIFE' 2005 - 2015," but that is not necessary. The key passages are summarized below. The full document provides a snapshot of water scarcity worldwide. This was the final report published by the UN after their decade-long focus on international water issues. I have highlighted some key elements in bold.

Click to read selected passages.

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

Figure 3.16: 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 an 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.

Credit: United Nations

The main takeaways from this video and article are:

• Economic water scarcity is when there is enough water in an area, but people don't have access to an adequate amount due to economic, political, or technological reasons
• Physical water scarcity is when there is not physically enough water to satisfy the needs of the people
• Arid areas being most prone to physical scarcity and those with social and/or political unrest most subject to economic scarcity;
• On a global scale, water scarcity is more of a distribution problem than a physical problem, according to the UN ("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.");
• Water scarcity impacts areas all over the world, including in some relatively wealthy countries.
• It is important to note that despite recent progress, the total number of people subject to scarcity or stress is likely to increase as population and water demand increase, and as the climate continues to change.

Though this TED-Ed talk was produced in 2013, the same issues exist today. As the narrator indicates, only about 8% of global fresh water consumption is from domestic uses (showering, teeth brushing, cooking, etc.) Most - about 70% (!) - is used for agriculture, and over 20% is used for industrial purposes (e.g. manufacturing, energy generation). This is very similar to the U.S. water use profile, as you will see in a second.

The United States Geological Survey (USGS) is charged with compiling the U.S.'s water use data. The most recent report is from 2015, which was released in June of 2018. Feel free to tool around with the data here, and go here for an interesting visualization of water use by category and state.

The chart below shows the percent of consumption different sectors of use are responsible for. As noted above, very little is used domestically and in the public supply (around 13% combined). (Note that irrigating lawns and watering gardens at home counts as domestic use, not irrigation.) You may be surprised by some of this, in particular that thermoelectric cooling is the single biggest user of total water in the U.S. (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.). Thermoelectric cooling just refers to cooling towers. Have you ever noticed that power plants are always located near a body of water? That is because the electricity generation process generates a LOT of waste heat. (Recall that power plants are generally 30% - 40% efficient, and so waste a lot of heat). Without constant cooling by a local water source, the plants would overheat. 

Figure 3.17: Summary of Estimated Water Use in the United States in 2015. As you can see by the chart, thermoelectric cooling was responsible for almost half of the water withdrawals in the U.S. in 2015, with irrigation very close behind. However, over 30% of thermoelectric water use was salt water, so irrigation is actually the biggest user of freshwater in the U.S.
 

Click for a text description

2015 Withdrawals by Category, in Million Gallons per Day

Category	2015 WithdrawAls 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.

It is important to keep in mind that it's not as easy as knowing how much water is being used. Unlike coal, natural gas, or other non-renewable resources, once water is "used," it does not disappear. (Recall that we have the same amount of water on earth now as we have had for thousands of years.) Rather, water is just moved into a different part of the water cycle. For example, with thermoelectric cooling, liquid water is converted to water vapor. It is then in a different part of the cycle, but is eventually converted back to liquid water (and perhaps solid) in the form of precipitation. If that precipitation falls over the ocean, it may stay there for a few days, or thousands of years. (The amount of time it stays in storage is called the residence time). If water is used to grow a food crop, it may evapotranspire in a matter of days, or it may stay in the plant, only to be consumed by an animal, and then perhaps by us, where it will eventually end up somewhere else. The UCAR Center for Science Education (who operates the National Center for Atmospheric Research) provides the following average residence times in the water cycle. It is important to point out that these are average residence times, and they are careful to note that there are exceptions to this:

A drop of water may spend over 3,000 years in the ocean before evaporating into the air, while a drop of water spends an average of just nine days in the atmosphere before falling back to Earth. 

Water spends thousands to hundreds of thousands of years in the large ice sheets that cover Antarctica and Greenland

...snow that falls in the winter may only stick around for a few days in mid-latitudes locations, where temperatures often rise above freezing causing the snow to melt, or up to six months closer to the Arctic

..Water stays in soil for around one to two months although this varies greatly.

Like many sustainability-related issues, freshwater availability is complex. When we use water, we may eventually get it back in a usable form. But keep in mind that when we use freshwater (e.g., to irrigate crops, cool power plants, etc.), much of it ends up as water vapor, and on average (according to UCAR) 80% of precipitation falls over the ocean, where the residence time is an average of 3,000 years. It is difficult to convert it back to freshwater when this happens. As you will see below, the overall trend is toward less freshwater being available. The take-home message here is that it is in our best interests to make sure we maintain an adequate level of freshwater as possible by minimizing& use. 

Okay, now you have an idea of what water scarcity is, and know different ways that human activity moves a lot of water in and out of different parts of the water cycle. You've also seen some indication of global water contamination issues. If you want to learn about some evidence of water scarcity, read through the suggested reading below.

Water Footprint

Given that most water is used for things other than direct household use, it stands to reason that there are "hidden" water costs to many of the things we do, use, and consume. Take a look around you, and think about what you ate today and yesterday. Have you ever thought about how much water was used for all of that "stuff?" Have you ever seen a water use label on a pack of hamburgers in the store? How about a loaf of bread? The label on your jeans? Neither have I and just like me, you would probably be shocked to find out how much water is used to produce most things. The Water Footprint Network defines water footprint as "the amount of water used to produce each of the goods and services we use" (source: 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. What is particularly nice about this organization is that they use peer-reviewed research as their information sources. The video below indicates some of the footprints of "everyday" products. The specific numbers are not meant to be gospel, but give you a good idea of water footprints. Note that the following 1 minute video has no audio narration.

Take a look at the Water Footprint Network's product gallery to see the (often surprising) water footprint of many common items.

Water and Equity

As with other sustainability issues, problems associated with access to fresh water is most acute in disadvantaged areas of the world. This includes low-income countries - particularly those in arid or semi-arid regions like sub-Saharan Africa - but also in impoverished communities in otherwise wealthy countries.

What About Desalination?

Since about 97% of the water in the world is salt water, why can't we just desalinate (remove the salt from) this abundant source so we can use it for freshwater? Well, actually we can! This is done all over the world. According to the International Desalination Association, an industry organization, there are over 20,000 desalination plants in 150 countries that supply some 300 million people with at least part of their needs. Aha - problem solved! Wait, what's that you say? It is very energy intensive? It has negative environmental impacts? It is expensive? (You didn't think it would be that easy, did you?)

Desalination is a very promising technology, but it is not without its problems. You are welcome to read through the articles below, but the bottom line is that desalination plants, while a proven technology, require 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."