Trying to wrap your head around figures for world water use is a truly mind-boggling exercise. The scale is simply too vast to relate to our everyday lives. You rapidly encounter astronomical figures like million gallons per day which are just the kinds of basic mathematical tools we need to begin understanding the sheer amount of water used globally. According to statistics from the USGS, the United States alone used a massive 355,000 million gallons per day in 2010, with this accounting for only a fraction of total water usage worldwide.
So where is it all going? What is it doing? Some uses are obvious enough, like the water that you drink, bathe in, flush your toilet with, or wash your car with. But these obvious uses only just begin to scratch the surface of the huge amount of water being used every single day. Millions of gallons a day are being used for purposes the average citizen might only have a fleeting awareness of. Water is used in industrial processes, used to irrigate crops, power thermoelectric turbines, and much more.
To really get a handle on where all the water goes, we decided to track water use by taking a long hard look at the numbers.
Comparing Water Use Habits: Residential v.s. Business
You’ve likely been encouraged in one way or another to save water. Conservation is certainly a great policy, reducing your impact on the environment and potentially even saving on your water bill. But at the same time, there is something a little disingenuous about the campaign to address water scarcity issues one family at a time. True enough that there is no reason to leave a leaky faucet to its own devices and clearly irresponsible to water your lawn during a drought, if we look at the statistics it quickly becomes obvious that domestic usage of water only accounts for a tiny fraction of overall water use.
Let’s have a look at those figures.
To really understand these numbers, we need to define a few terms and also understand the different ways in which we all contribute to water use. The most direct area that the average person contributes to on this chart is Public Supply. Public Supply accounts for water distributed by a public or private company to businesses, residences, and industrial plants. About 57% of all Public Supply water is used domestically in homes for activities like drinking, cooking, washing clothes and dishes, bathing, and other household uses. The rest of Public Supply water is used in commercial buildings to operate businesses, used for public water supplies like fountains, used for pools, used for industry and manufacturing, and other purposes.
This is the area of the chart you’d be aiming to cut into when you make sure to turn off the hose as quickly as possible or cut your shower a few minutes short. In total, Public Supply accounted for only 12% of water use in 2010. With only about 57% of that going towards domestic, only about 6.84% of total water use in 2010 was used by domestic households. Compare that with a truly staggering 45% for Thermoelectric Power and a whopping 33% for irrigation!
How Water Keeps The Lights On
When you plug in your computer or flick on the light switch, the last thing you probably think about is how you are actively using water in order to power your gizmos. Those familiar with the types of thermoelectric generators which make up much of the backbone of our electric grid know well the huge cost of water required to operate these generators. Water is used to create steam, turn turbines, and as a coolant for a variety of systems, making water often the most essential ingredient in generating electricity for our homes and cities.
Although the fuel that powers these generators often attracts much more focus and is much more valuable and scarce, water is ultimately the main workhorse that allows the modern electrical grid to operate the way it does. Despite the towering clouds of steam which rise visible and endless from the smokestacks of power plants across the globe, the water cost of electrical generation is something few average people give any thought at all. The USGS estimated that in 2010 it took on average 16 gallons of water per kilowatt hour of electricity produced.‘
Where Electricity Goes, Water Follows
So where is all the electricity going? To find out, we consulted this very illuminating chart from epa.gov:
Although the Residential sector has the largest share of the chart with 37% consumption, overall the combination of 35% from the Commercial sector and 27% from the Industrial sector still leave business-related use far ahead of the consumption of electricity in residential homes by everyday families.
In the United States, by far the best way to conserve for both businesses and private residences is by reducing electricity consumption. Reducing electricity consumption has a cascading effect which reduces consumption of precious and extremely limited fuel sources, uses less water, creates less emissions, and immediately saves money.
As important as it is for everyone to learn how to minimize their electricity usage, business owners, corporate managers, and industrial leaders are responsible for the consumption of orders of magnitudes more electricity than private residences. The impetus should be placed on them to make environmentally wise and resource-conservative decisions much moreso than everyday families. The responsibility to consume resources wisely rests with both the individual and the institution.
The Difference Between Water Use and Water Consumption
As we explore these numbers, it is important to keep in mind the important distinction between water use and water consumption. When we refer to water use, we are not necessarily implying that the water is gone after we’ve finished using it. If a power plant requires 1,000 gallons of water for cooling but returns 900 gallons to the watershed once it is done, we would say the power plant’s total water use would be 1,000 gallons, whereas its total water consumption would be 100 gallons.
Water is considered “consumed” when it does not return to the original water source. This could mean it was lost or spilled, evaporated into the atmosphere, incorporated into a product, or transported elsewhere. Although water which is used is not necessarily consumed, used water returned to its source is rarely of the same quality as before it was used. This is why waste water treatment is by far one of the most important assets of the modern world.
Waste water and water consumption was the focus of the United Nations Educational, Scientific, and Cultural Organization’s (UNESCO) 2017 World Water Assessment Programme (WWAP.) This expansive resource includes tons of great data and suggestions for moving forward in improving utilization of waste-water. Check out the chart below for a visual look at where water consumption is at its highest.
“The AQUASTAT database of the Food and Agriculture Organization of the United Nations (FAO) estimates global freshwater
withdrawals at 3,928 km³ per year. An estimated 44% (1,716 km³ per year) of this water is consumed, mainly by agriculture through evaporation in irrigated cropland. The remaining 56% (2,212 km³ per year) is released into the environment as wastewater in the form of municipal and industrial effluent and agricultural drainage water (see Figure 1).
A country’s level of industrial and municipal wastewater treatment is generally a reflection of its income level. On average, high-income countries treat about 70% of the wastewater they generate, while that ratio drops to 38% in upper middle-income countries and to 28% in lower middle-income countries. In low-income countries, only 8% of industrial and municipal wastewater undergoes treatment of any kind (Sato et al., 2013). This exasperates the situation for the poor, particularly in slums, who are often directly exposed to wastewater due to a lack of water and sanitation services.” – (UNESCO 2017 WWAP, Page 9)
Understanding this distinction between use and consumption is an indispensable tool towards creating a healthy mindset for conserving and properly respecting our water resources. If you do not understand the difference between use and consumption, it may seem like all water which is used is consumed, when this is not the case. The more waste water that can be captured and properly treated leads to more energy and expenditures being saved, and more efficient systems being achieved.
In this area we still have a long way to go worldwide. Quoting the 2017 WWAP linked above, we find the authors concerned with a lack of emphasis on wastewater capture and treatment worldwide: “it is clear that, worldwide, the vast majority of wastewater is neither collected nor treated. ”
Agricultural Irrigation: The #1 Consumer of Water
Although in the United States thermoelectric power accounts for more water use than agricultural irrigation, worldwide agricultural irrigation is the single largest user and consumer of water. Agriculture accounts for 70% of global water use, followed by industrial at 20% and domestic at 10%, according to United Nations Water.
Agriculture is so intensive in not only water usage but consumption due to both the nature of irrigation and the inherently water-intensive requirements of growing mass quantities of crops. When water is used for irrigation, little to none of it is collected as waste water. In many cases the vast majority of water is actually lost to the atmosphere due to evaporation, never even serving its purpose to hydrate the plants. What does make it into the plants is transpired through their leaves into the atmosphere, or incorporated into the plant and shipped away after harvest.
Your Food Is Thirsty
The reason agricultural water consumption soars so high above other uses of water is simple: plants are thirsty. Growing healthy, happy, produce-yielding crops requires substantial amounts of water to promote the plants throughout their life cycle. Once the crop has been harvested, water is literally shipped away in the form of produce exported from its source.
The water-intensive nature of farming crops has been highlighted many times in the public spotlight. Almonds have been famously vilified, perhaps somewhat unfairly, as a major contributor to California’s historic drought. In 2014 it was calculated that almond, which can take as much as an entire gallon of water to produce a single nut, accounted for a full 10% of historically dry California’s water consumption.
In this Huffington Post Article, the author calculates some data from a UNESCO-IHE report entitled “The green, blue and grey water footprint of crops and derived crop products” to get a handle on the actual cost in water to produce common foods.
Some of the results are quite shocking. A single pound of rice can require up to 299 gallons of water to produce. A pound of wheat bread can take up to 193 gallons of water. It takes only 290 gallons of water to produce a pound of potatoes, or a remarkably conservative 26 gallons to a pound of tomatoes. Meanwhile, something especially heavy like olive oil takes a whopping 1,729 gallons of water per pound! But is still bested by the ever-thirsty almond, which requires a staggering 1,929 gallons per pound, about the same as cashews.
Livestock Drink Twice
If you looked at the graph above of gallons of water used to per calorie of different food stuffs, you likely noticed that beef is the worst offender on the list, requiring nearly 1.8 gallons of water per calorie, or about 1,847 gallons of water per-pound of beef. While beef consumes the most water per pound of almost any food stuff, this is a trait of all livestock: they drink twice.
Any livestock that is fed with grains or crops absorb the water cost of growing those crops into their final product. You may have also noticed in the chart of U.S. water usage at the top of this article that Livestock account for about 1% of daily U.S. water usage, or around 2 billion gallons per-day.
Food Waste = Water Waste
With the huge cost of water per pound for food items, food waste is one of the single largest ways water waste can be reduced both on the level of the individual and worldwide. Based on statistics from the City of Philadelphia, the average person uses about 101 gallons of water everyday. If you go shopping one afternoon and forget to bring in a sack of groceries, resulting in a pound of hamburger rotting in your car, you’ve wasted a full 18 days of water use!
How much is that? In everyday terms, for the water cost of a pound of beef you could do about 123 loads of laundry. You could take around 92 10-minute showers, about the average shower for Americans. Or you could drink 14,776 8-ounce glasses of water.
Even on the level of the individual, the ability to relatively easily and thoughtlessly waste vast quantities of water through their food is remarkable. But on a global scale, the amount of food waste is unfathomable. According to this article from The Guardian, as much as one-third of food produced globally is wasted, an inconceivable 1.6 billion tons of food with a market value of a cool $1 trillion. As the title of the article suggests, a full 50% of all food produced in the United States is wasted and thrown away. The volume of wasted food is so vast that disposing of it has become a problem on an industrial scale. From the article:
“Within the US, discarded food is the biggest single component of landfill and incinerators, according to the Environmental Protection Agency. Food dumps are a rising source of methane, a far more powerful greenhouse gas than carbon dioxide. But experts readily acknowledge that they are only beginning to come to grips with the scale of the problem.”
In the US and worldwide, the water lost from food waste is by far the biggest example of pure waste anywhere in the statistics for global water usage. With a full third of global food produce going to waste, the amount of water waste is beyond compare.
While power generation accounts for about 15% of global water usage, very little of the water used for generating electricity is actually consumed. Based on the numbers from this study, only about 8.9% of the total water used for generating electricity is actually consumed, around 52 cubic kilometers annually across the globe. While the water quality may suffer, the vast majority of water used for energy production can be returned to its water source.
In contrast to this type of use, food waste is a total loss. There is no way to return the water to its source, or even harvest the water as waste water. The vast majority of the water lost from food waste is consumed during the growth of the crops or life cycle of the livestock and is completely unrecoverable. The tiny remainder within the produce itself will decompose and rot, leaving you with a sticky mess in the best case scenario, and an environmental catastrophe in the worst.
With as much a 2,769 cubic kilometers of water being withdrawn annually for agricultural purposes, the total amount of water consumption from food waste dwarfs the entirety of the water consumption bill of every other sector. As we explored above, agriculture use tends to be far more consumptive than these other sectors, so much more of this withdrawn water is being consumed and not recovered as waste water.
The total water consumption from food waste is difficult to estimate, but without a doubt is staggering. Adding insult to injury, much food waste happens after the food has already been distributed to stores or consumers. The process of transporting and storing the food incurs additional costs in fuel and water, and once deemed garbage additional transportation is often necessary for disposal, another process that can cost time, energy, and water!
From the statistics above, it becomes clear that the main area of water waste the average everyday person is responsible for is from food waste. Food waste is a global problem which impacts every population regardless of socioeconomic status, but for different reasons.
In developing nations, lack of access to proper food storage technologies can create serious food waste issues for the populations most in need of calories. Meanwhile, in wealthy developed nations where incomes are high and food prices are low, food waste is encouraged by the huge abundance and laissez-faire approach to food waste.
Despite paying little mind to how much food they are wasting, food waste has a real economic impact on the American family. The NRDC estimates that an average 4-person household in the US loses approximately $1,350 to $2,275 each year in wasted food. With American families throwing out on average around 25% of the food they buy, tackling food waste is the single most impactful way the average person can reduce their water footprint and truly save water.
However, the consumer only tells part of the story. Food waste occurs at every stage of production and distribution. Fruits and vegetables deemed sub-par are never harvested, left in fields to rot. Quality control and damages removes even more produce during processing and packaging. Losses and damages occur during transport and distribution, and once the food makes its way to a retailer it has a very limited window before it is past its Sell By date and must be disposed of. Despite much of it being edible, vast quantities of items past the date on their Sell By label are disposed of everyday by supermarkets and grocery stores around the world.
Respecting the huge cost in water that our food represents is a vital step towards making real strides towards worldwide water conservation. Improvements in technology have lead to more efficient irrigation systems, and increased understanding of the science of farming lead to more effective practices. Progress also leads efficiency forwards in areas like electricity generation and industrial use, where there is constant economic incentive to make processes more resource efficient and cheaper. These forces continuously contribute to reductions in water usage and consumption across all sectors.
Increasing global focus on renewable sources of electricity has the future poised for a much less water-intensive means of powering our electrical grid. Technologies like wind and solar have practically no water consumption or use at all. Even hydroelectric, which relies entirely on water use, has very little water consumption cost and minimal impact on water quality.
However, one area of water consumption which does not benefit from the progress of science and technology is food waste. Our attitudes towards food and the way we use, store, distribute, and dispose of it are decisions we have the ability to make immediate changes to. These problems require no new developments to solve and we will not awake one day to find them solved by technology.
Making A Difference
Now that you know where the water is really going, you are much better equipped to make wise decisions about how to properly utilize water resources. While it is important to make small steps to reduce your direct contribution to water waste, like minimizing watering your lawn, using low-flow toilets, taking conservative showers, not washing your car during a drought, steps like these actually have a much lower impact on your water footprint than the amount of water cost represented by the food in your fridge and pantry.
When you turn on the tap or hold a strawberry, the water content is very obvious and tangible. Less obvious is the water you use every time you use electricity in your home. Cutting back on electric usage will reduce your overall water footprint and create less emissions, not to mention saving on your electric bill.
While analyzing how much food you waste and taking steps to minimize and mitigate might not directly save you on your water bill, it is the single most important thing you can do to reduce your water waste! It will also have a very real impact on your food budget, potentially offering huge savings on money you are otherwise throwing away!
Ultimately, resource conservation is a philosophy which must be instilled into every individual. Only when we all understand and take responsibility for the use of resources in our environment can we hope to use what we have to its greatest possibilities. With the right understanding of how to better utilize what we have, everyone can be better poised to benefit from the incredible abundance of the modern era.
How Do You Conserve Water?
Do you have an interesting method of saving water? Let us know in the comments. We’d love to hear from you!
- Total Water Use in the United States – United States Geological Survey, water.usgs.gov
- Public Supply Water Use – United States Geological Survey, water.usgs.gov
- Water & Energy Efficiency By Sectors – United States Environmental Protection Agency, epa.gov
- Thermoelectric Power Water Use – United States Geological Survey, water.usgs.gov
- Electricity Customers – United States Environmental Protection Agency, epa.gov
- What’s the Difference Between Water Use and Water Consumption? – Paul Reig, World Resources Institute, wri.org
- 2017 World Water Assessment Programme (WWAP) – United Nations Educational, Scientific, and Cultural Organizations (UNESCO) unesdoc.unesco.org
- UN-Water Statistics Details: Agriculture is the biggest water user – UN-Water, unwater.org
- Gallons of water per calorie of food items – David Roberts (Twitter: @drvox) twitter.com
- Stop Vilifying Almonds – Eric Holthaus, slate.com
- The Thirsty West: 10 Percent of California’s Water Goes to Almond Farming – Eric Holthaus, slate.com
- This Is How Much Water It Takes To Make Your Favorite Foods – Katherine Boehrer, huffingtonpost.com
- The green, blue and grey water footprint of crops and derived crop products – UNESCO-IHE Institute For Water Education, waterfootprint.org
- Livestock Water Use – United States Geological Survey, water.usgs.gov
- Gallons Used Per Person Per Day – City of Philadelphia, phila.gov
- Half of all US food produce is thrown away, new research suggests – Suzanne Goldenberg, theguardian.com
- UN-Water Statistics Details: 15% of global water withdrawlas used for energy – UN-Water, unwater.org
- The water consumption of energy production: an international comparison – Center for Water-Energy Efficiency, University of California, iopscience.iop.org
- AQUASTAT World Water Withdrawal by sector, around 2010 – Food and Agriculture Organization of the United Nations, fao.org
- Wasted: How America Is Losing Up to 40 Percent of Its Food from Farm to Fork to Landfill – Dana Gunders, Natural Resources Defense Council, nrdc.org
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Ever wonder where all that water goes? In this in-depth examination we dive head-first into the numbers to find out where water goes and how we can use it better.