It takes water to make or produce almost everything that people buy, use, consume, eat/drink, and do.
In this guide below, we explain what a water footprint is, how it can be used, what virtual water is, and more.
Summary – Water Footprints, & Virtual Water
What Is A Water Footprint?
A water footprint is a tool or concept that provides a rough estimate of how much water it takes to produce or do something
Several reports indicate it’s not to be taken as definitive though
What Things Can Have A Water Footprint?
We give examples of things that can have a water footprint in the guide below
Examples Of Water Footprints In Different Things
In the guide below, we link to other guides where we outline the potential water footprints of different things
Different Ways To Express A Water Footprint
There’s different ways to express a water footprint, which we list in the guide below
Different Types Of Water In A Water Footprint – Blue, Green, & Grey
Other than a single water footprint number, the total water footprint can be categorized into the blue, green and grey water footprints
Blue water is surface water and ground water, green water is rainfall, and grey water is water used to dilute waste water in manufacturing
We provide more information on these types of water in the guide below
Other Considerations In Calculating A Water Footprint
There can be other considerations in calculating a water footprint, such as:
– Considering the entire lifecycle of something vs one or multiple individual stages of that lifecycle
– Considering direct vs indirect water use (which is the same as visible and invisible water use)
– Considering withdrawn vs consumed water
– Considering other types of water other than those already mentioned
How each of the above are included or excluded in the water footprint calculation can change the final water footprint figures.
We explain each in further detail in the guide below.
Water Footprints For The Same Type Of Product Can Differ
Water footprints for the same type of product can differ between countries, between producers (who use different production practices), and so on
We provide reasons for this in the guide below
Potential Limitations Of Using A Water Footprint As A Tool
Similar to the use of carbon footprints, there are a number of limitations with using a water footprint, and we’ve listed some of these limitations below
Water footprints are not definitive, and because of these limitations, they likely shouldn’t form the sole basis or majority basis of water strategies, water management plants or water solutions
What Might Be The Best Way To Use A Water Footprint?
We outline how a water footprint might be used best as a tool to help address water issues in the guide below
What Might Make Water Footprints Important?
A water footprint might be one tool amongst many that can help measure the use of fresh water resources, and may also help in providing potential solutions to some global water problems
But, there’s already several potential solutions to manage water more sustainably across society.
Water footprints may also highlight some general water use trends, and help make general comparisons between products and things
Importing & Exporting Water Footprints
Countries can import and export a certain % of their overall water footprint with the different products they trade
Countries with water resource and water supply issues (such as being water stressed or scarce) may especially benefit from importing a larger % of their water footprint
Some countries currently source the majority of of the water they consume from outside the country
We provide examples of majority water importers, and also specific water intensive products that may be imported by some countries in the guide below
Water Footprint Assessment & Calculation Tools
We’ve listed resources that have tools and calculators for estimating water footprints in the guide below
What Is Virtual Water
Virtual water is essentially the same as indirect water – it’s the water used in making something, that is usually used further up the supply chains and not seen
Countries Using ‘Virtual Water’ As A Tool
Some countries have used the virtual water measurement as a tool, whilst others have decided against using it
What Is A Water Footprint?
A water footprint is a tool or concept used to estimate the amount of water it takes to produce, or do something
It’s important to point out that it’s a general estimation only, and isn’t a definitive measurement
The watercalculator.org and waterfootprint.org resources in the list below have further definitions of what a water footprint is.
What Things Can Have A Water Footprint?
Anything that uses water in it’s lifecycle can have a water footprint – this is essentially everything.
Just a few common examples include:
– Food and beverages (and even specific types of diets)
– Everyday products and services (shirts, shoes, electronics, using different energy sources, etc.)
– Activities (like washing hands, having a shower, watering the garden, etc.)
– Individual people
– Households
– Individual companies
– Entire countries
Examples Of The Water Footprints Of Different Things
These guides contain more information on how much water it takes to make different things
How Much Water It Takes To Make Different Foods & Beverages
How Much Water It Takes To Make Everyday Products & Things
How Much Water Different Energy Sources Need To Produce Electricity
How Much Water Common Household Appliances Use
Countries That Use The Most Water
Industries That Use The Most Water
waterfootprint.org and earthmagazine.org also have other examples in their resources
Different Ways To Express A Water Footprint
A water footprint might be expressed in several ways, such as:
– The total volume of water used
– Water used per unit of weight of produced
– Water used per nutritional unit or calorie produced (in the case of food)
– Water used per dollar of production
– Plus, other expressions
Different Types Of Water In A Water Footprint – Blue, Green & Grey Water
There’s different types of water that can be measured in a water footprint – blue, green, and grey water
Sometimes they are separated in a water footprint calculation, but sometimes they are included together the total water footprint figure (which is why it’s important to check what a water footprint calculation is composed of)
Calculating the different types of water gives a more accurate or detailed picture of the final water footprint figures
Green water might be most preferable from a sustainability perspective, as rainfall is renewable
But, blue water might be sustainable in regions that are water abundant, or that have sustainable water management practices, just as a few examples
wikipedia.org indicates that: ‘[Not all water types or sources are of] equal value’, and sustainability might be one of the things they are referring to here
In some countries and in some farming operations, green water may make up most of beef’s water footprint, but it can differ around the world
Below are more detailed descriptions of each of the different types of water, more information on the beef water footprint example, and also sources that have more information available on the different types of water
Explanations Of Blue, Green & Grey Water
An explanation of those three types of water might be:
– Blue Water
The amount of surface water and ground water used.
It can be used directly, or evaporated.
– Green Water
The amount of rainfall used.
It can be used directly, or evaporated.
– Grey Water
The amount of freshwater used to dilute waste water from manufacturing.
Diluted waste water usually has to meet water quality standards determined by regulations in the area.
Example Of Blue, Green & Grey Water In Beef
As one example for beef from waterfootprint.org:
The production of one kilogramme of beef requires approximately 15 thousand litres of water (93% green, 4% blue, 3% grey water footprint).
[But] There is a huge variation around this global average [and it] … depends on factors such as the type of production system and the composition and origin of the feed of the cow.
More Information On The Different Types Of Water
The watercalculator.org, waterfootprint.org, and earthmagazine.org resources listed all go into greater detail explaining each of these types of water in a water footprint.
The waterfootprint.org, and earthmagazine.org resources both give examples of how the types of water make up different shares of different products.
earthmagazine.org also further discusses how China, Mongolia etc. use blue, green and grey water in their article
Other Considerations In Calculating A Water Footprint
Some of the different considerations in calculating a water footprint might be:
Considering An Entire Lifecycle Of Something vs Individual Stages Of That Lifecycle
A water footprint can be calculated for the entire lifecycle of something, or just a specific stage (or specific stages) of the lifecycle
Examples of stages are the production stage, usage/operation stage, waste stage, and so on
We’ve outlined examples of the stages of different products and things in this guide.
Considering Direct vs Indirect Water Use (& Visible & Invisible Water Use)
Water footprints can include just the direct water usage, or both the direct and indirect water usage
Direct water use (and visible water) is the water we use directly that we see (or that is used on-site somewhere)
Indirect water (and invisible water) is the water used further up the supply/production chain that a consumer doesn’t see (or, that is used off-site somewhere).
Many industries actually use most of their water indirectly.
Considering Withdrawn vs Consumed Water
There’s a difference between withdrawn, and also consumed water – different water footprints may or may not include both in the calculation
Withdrawn water is water that is used, but returned to the water supply – so, it can be used again
An example of withdrawn water is water used for hydroelectricity that is returned to the river after it’s use.
Consumed water on the other hand is water that is removed permanently from the water supply once it’s been used
Consumed water might be considered as non recoverable water.
An example of water consumption is the water used to irrigate crops, that is either absorbed, or evaporated.
Sustainabilityreport.duke-energy.com defines water withdrawn vs water consumed as:
Water withdrawn is the total volume removed from a water source such as a lake or river. Often, a portion of this water is returned to the source and is available to be used again.
Water consumed is the amount of water removed for use and not returned to its source
One example of consumptive water use vs withdrawals, according to watercalculator.org, is:
… agriculture accounts for 38 percent of the [United States’] freshwater withdrawals but it accounts for approximately 80 to 90 percent of the nation’s consumptive water use …
As another example, we identify in this guide how the vast majority of the water that Australia extracts each year as a country is non-consumptive water.
Considering Other Types Of Water
Other types of water other than those already mentioned might include evaporated water, polluted/contaminated water, and any other water that becomes unusable (such as degraded water, or water that needs to be treated for re-use), or is immediately removed from the water supply.
Considering Different Types Of Water From A Sustainability Perspective
When looking at water use from a sustainability perspective, it’s important to consider the difference between consumed water and withdrawn water, rainfed water (which can be renewable) and non renewable water resources, and also whether the water is treated, or treated and re-used/recycled after use.
… ultimately, some water use is more sustainable, and some is less sustainable, depending on the type of fresh water used, where it comes from, and what happens to the fresh water after it’s used
So, not all water use always bad an unsustainable – it depends on costs and benefits of using that water, and how water is managed as a resource
Water Footprints For The Same Type Of Product Can Differ
Water footprints for the same type of product can differ because of different factors and variables between where those products are sourced/made.
For example, water footprints can differ between countries, between different producers, and so on.
This is the case with beef and other food products in different countries and from different farms, where variables like the predominant farming systems used (grain vs grass fed just as one example, or free range vs factory farmed as another), climate, and other factors, can lead to different water footprints in different products.
The same can be said for different crops which might need more water/irrigation in climates that are dry and hot compared to other climates
waterfootprint.org and wikipedia.org discuss this in further detail, and give examples.
Potential Limitations Of Using A Water Footprint
Using a water footprint as a tool for measuring water use can come with limitations.
Below we list some of those potential limitations:
– Not All Water Footprints Have The Same Inclusions & Exclusions, Or Are Calculated In The Same Way
For example, some might analyse the whole lifecycle of a product or thing, and others just one stage
As another example, some might not specify the types of water in the water footprint whilst others do
– Data Collection Can Be Expensive & Challenging
It’s not always possible to collect all water usage data for a product or thing
Sometimes the data is not available, and sometimes there’s restrictions or difficulties in getting some data
So, some water footprints may only tell part of the water usage picture
– Water Footprints Don’t Provide Context On Water Resources, Water Supply & Water Management In A Specific Region
Water footprints only take into consideration water usage, but water usage is only one aspect of the overall water management picture in an area
A water footprint doesn’t provide context on the other side of water management, such as water resources, water supplies, and the sustainable stewardship of water
In places where water resources are abundant (Russia and Brazil are examples of countries with large renewable fresh water supplies), supply is good, and the overall stewardship of water is more sustainable (or there’s a history of sustainable water management) – larger water footprints might not be as much of a problem as places where water resources and supplies are scarce or experiencing issues.
The same goes for wetter climates with more rainfall compared to drier and hotter climates with less rainfall
From this perspective, the same water footprint number for the same type of product might be sustainable in one region, but not in another.
But, water footprints don’t tend to make this distinction.
So, local conditions and context of water use should be considered.
From wikipedia.org:
[A water footprint] fails as an indicator of [both] environmental harm [and also as an] indication of whether water resources are being used within sustainable extraction limits.
– Only Measures Water Usage, & Doesn’t Take Into Account Economic Or Social Benefits Of Water Use (Along With Other Potential Benefits)
Water footprints measure water usage, and the higher the water footprint, the worse it may look to some people.
However, not all water use is bad.
Water use may lead directly to economic and social benefits, such as employment, income, contributing to an economy, and so on.
In some lower income regions, water use may contribute to people’s entire livelihoods
[Sri Lanka is an example of a place where rain is abundant, and people depend on water for employment and their livelihoods] (earthmagazine.org)
Each local area will have different tradeoffs in terms of the economic and social benefits that water use provides, depending on local variables and factors.
The same thing applies to other potential benefits of water use – instead of relying on one water footprint calculation, the full pros and cons of water use should be weighed up.
– Doesn’t Take Into Consideration Alternate Uses For Water, If Any, & Also What The Benefit Or Disadvantage Of Alternate Uses For The Water Might Be
Sometimes there’s an alternate use for the water that’s been used, and sometimes there isn’t
In the case that there is an alternate use for the water, a water footprint doesn’t identify what it might be
It also doesn’t outline the inputs and resources required for that alternate use, or what the overall opportunity cost of that alternate use might be in a specific geographic region.
From wikipedia.org:
[Just because less water is used in one activity, it doesn’t mean that saved water can be used in another activity, and additionally, the alternate use for the water might not be economically friendly]
– Doesn’t Always Identify All The Different Types Of Water, & How Sustainable They Might Be
For example, blue, green and grey water might be measured in some water footprints
Using rainwater (which is renewable) for rain fed farming, over irrigated water for crop farming might be more sustainable in some instances
But, newer types of water such as desalinated water or recycled waste water might not be considered in a water footprint
Once through cooling at power plants is another type of water that might not be considered or calculated (watercalculator.org writes about once through and closed cycle systems)
– There May Not Be A Distinction Between Imported & Exported Water Footprints
Another factor some water footprints may not take into account is what portion of total water use is imported water, and what part is exported water
Some countries import a lot more than others, and some export a lot more than others
Therefore, water footprints may not always show the largest net importers and net exporters, and the total % of their net imports and exports
– Only Measures Water Usage, & Not Other Sustainability Indicators
Water use is not the only indicator of sustainability – there are many others
Therefore, a water footprint is limited in this regard
From earthmagazine.org:
A sustainability index or indicator should capture all the important elements of a problem you are trying to solve.
Virtual water and water footprints, which don’t capture all of the necessary elements, have been misused as sustainability indices.
– Other Information On Other Potential Limitations
earthmagazine.org discusses the limitations of a water footprint in greater detail.
globalwaterforum.org, globalwaterforum.org and wikipedia.org also discuss the issue of the limitations of a water footprint in their resources
What Might Be The Best Way To Use A Water Footprint?
Reports like those from earthmagazine.org might suggest that concepts like ‘water footprints’ and ‘virtual water’ might only be one tool used in much larger discussions about sustainable water resource management
They may be best used in an integrated approach with other far more advanced and detailed water usage stats, tools and information being available to help make decisions
Some reports go as far as to suggest that a water footprint is a concept only, and shouldn’t be used in any meaningful way to make key water management decisions at the social or government level
earthmagazine.org goes into far more detail about what might be the best way to use water footprints as a tool, which we’ve paraphrased:
Patterns of water use happen on the local level (like cities), and not as much the country or global level [so, water footprints and solutions should be aimed at the local level]
Factors like what water is being used for, the value being created, what a city is getting for their water use, how effective the water use is, and other factors like water dependency should be incorporated into water measurements
[Types of water that make up a water footprint should be identified]
[The lifecycle stages included in the water footprint should be identified]
[Confusion and inconsistencies can be minimized] if the scope and goals of the virtual water footprint assessment are clearly laid out in a brief
Standardization of virtual water reporting may help
[For corporations, water footprint may help them] understand where their water comes from, help them identify potential risk, and help them understand various other things about their water use
Businesses may be in a better position than governments to pick up unsustainable water use, or other water issues (like overuse and pollution), because they have more data on where the materials and things that use water are coming from
Every country, and every company, faces a different set of challenges in managing water use – [so, regulations on reporting water use and managing water use] can be ineffective [compared to a more individual approach]
Importing & Exporting Water Footprints
Countries may import or export a certain % of their total water footprint.
Countries with better freshwater resources, more favorable climates, and better technology can export to countries without these things (i.e. to countries that have drier climates, that are more water scarce or water stressed, or that have water problems)
This can particularly be the case with crops and foods (which can take a lot of water to grow)
Some countries like Japan may have a large % of the water they use that is sourced externally (i.e. outside the country)
Overall, virtual water associated with global food trade might be increasing over time
Examples Of Countries Importing Or Exporting Water Footprints
– Soybeans
One example is China importing soybeans according to earthmagazine.org
– Oranges
wikipedia.org mentions that ‘… countries like Palestine discourage the export of oranges (relatively heavy water guzzlers) precisely to prevent large quantities of water being exported’
– Wheat
wikipedia.org also notes that ‘When a country imports one tonne of wheat instead of producing it domestically, it is saving about 1,300 cubic meters of real indigenous water.’
How Much Of A Countries Water Is Sources Externally
In regards to how much of a country’s water is sourced externally (i.e. how much of that country’s water footprint fall outside the country), one set of data by wikipedia.org indicates:
[For China it’s about 10% of their water footprint that falls outside the country, Japan is about 77% and the US is about 20%, with] The largest external water footprint of US consumption [being the] Yangtze River Basin, China.
Virtual Water Associated With Global Food Trade – Increasing Over Time
earthmagazine.org outlines that virtual water volume associated with global food trade has doubled from 1896 to 2007, and virtual water trade in the US has quadrupled.
Water Footprint Assessment & Calculation Tools
You can find more tools for assessing and calculating water footprints at waterfootprint.org
There’s also a Water Footprint Calculator at GRACE (gracelinks.org)
What Is Virtual Water?
Virtual water is the water involved in making something, that is usually not seen, and is usually also usually used further up the supply chain.
It’s essentially the same thing as indirect or invisible water, and is sometimes called ’embedded water’, or ‘hidden water’.
Virtual water may especially be important where products and services use most of their water at a lifecycle stage other than the usage stage
watercalculator.org, waterfootprint.org and wikipedia.org also discuss the concept of virtual water.
watercalculator.org gives an example of a smartphone having a large virtual water footprint:
… in the case of the smart phone, [grey water which is the water used to clean and dilute the wastewater] makes up the largest portion of its total water footprint …
thewaterweeat also provides a good example of the water hidden in a piece of beef
The vast majority of it comes from the feed required to feed cattle, and the remainder comes from water the cattle need to drink, and finally water for servicing farmhouses and slaughterhouses.
Examples Of Countries That Have Used ‘Virtual Water’ As A Tool
Some countries have used virtual water as a concept and tool, whilst others have decided against it.
From earthmagazine.org:
Some countries like Spain and India have used the [‘virtual water’] measurement concept for help in forming regulations and policies
[Other countries like Australia and the Netherlands have taken the opposite approach – saying the measurement of virtual water has little practical value for governmental decision making]
Sources
1. https://www.theguardian.com/news/datablog/2013/jan/10/how-much-water-food-production-waste
2. https://www.watercalculator.org/water-use/the-hidden-water-in-everyday-products/
3. http://waterfootprint.org/media/downloads/Report16Vol1.pdf
4. https://www.watercalculator.org/footprints/what-is-a-water-footprint/
5. http://waterfootprint.org/en/resources/interactive-tools/product-gallery/
6. http://waterfootprint.org/en/water-footprint/what-is-water-footprint/
7. https://www.earthmagazine.org/article/virtual-water-tracking-unseen-water-goods-and-resources
8. https://get-green-now.com/food-water-footprint-infographic/
9. https://waterfootprint.org/en/resources/waterstat/
10. http://www.gracelinks.org/1408/water-footprint-calculator
11. https://en.wikipedia.org/wiki/Virtual_water
12. https://news.thomasnet.com/imt/2012/04/10/down-the-drain-industry-water-use
13. https://www.motherjones.com/food/2015/04/blue-jeans-cars-microchips-water-use/
14. http://www.globalwaterforum.org/2013/10/22/water-footprints-policy-relevant-or-one-dimensional-indicators/
15. http://www.globalwaterforum.org/2012/05/14/virtual-water-some-reservations/
16. https://www.watercalculator.org/water-use/the-water-footprint-of-energy/
17. https://www.watercalculator.org/footprints/rainwater-green-water-footprint/
18. http://thewaterweeat.com/
19. https://www.watercalculator.org/footprint/foods-big-water-footprint/
20. https://sustainabilityreport.duke-energy.com/2008/water/withdrawal.asp
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