- Embedded Water Definition
- Importance of embedded water
- Importance of embedded water in food
- Discussion points

Embedded Water Definition

Embedded water is the amount of water used in the entire process of producing, retailing and consuming (cooking for example) a product. It is also referred to as virtual water, embodied water or shadow water. The concept is very similar to embedded carbon (see Carbon Footprinting and Labelling factsheet).
 

Importance of embedded water

It is estimated that the average Briton drinks between 2 and 5 litres of water per day and will use about 145 litres for cooking, cleaning, washing and flushing. If the embedded water used in the production of the goods people consume is also taken into account however the daily use per person in the UK may be nearer 3400 litres (Source: Waterwise).

Areas of water consumption in the UK

Source: Waterwise
 

Importance of embedded water in food

In the graph above, water embedded in food represents the majority (65%) of total water use in the UK. While the exact figure may be disputed it is clear that significant amounts of water are used in the production and processing of food products. The amounts vary by food category. By way of illustration, a number of common food products are presented below with an estimate of their embedded water for a given weight or volume.

Estimates of water embedded in different products

Source: Waterwise

It is clear that different types of food require different amounts of water to produce them and so embedded water differs greatly by category. It is important to understand how these figures have been calculated. The hamburger is taken as the example.

Example of embedded water in beef production

Source: Waterwise

Again, while the actual figures may be challenged water is clearly required in producing cattle feed (grain and roughage in this case), providing drinking water for cattle and in other services during production and processing.

The water embedded in products is a growing area of awareness. In the UK the Food Industry Sustainability Strategy Champions’ Group on water concludes that “Both retailers and manufacturers should have regard to the ‘embedded water’ in the products they source, the associated carbon, and the potential environmental impact these factors may have, particularly on the products’ countries of origin”.
 

Discussion points

There are a number of discussion areas regarding embedded water.

Origin and impact

Embedded water within similar products varies between nations due to different climates, irrigation and production techniques and technology. For example it has been estimated that a kilogram of oranges from Australia has up to three times the embedded water of a kilogramme of oranges from the USA. Additionally, different species of the same plant can differ in water requirements. Most importantly, similar amounts of water used in drought prone countries have a much greater impact than in high rainfall countries.

Trade

Within the UK the amount of water embedded within crops is relatively low compared to other countries, but NGOs have argued that by importing items with high embedded water from drought prone countries (e.g. cotton from Egypt) the UK is acting irresponsibly and ‘exporting drought’. UK World Wide Fund for nature (WWF-UK) estimates that 62% of UK embedded water is derived through imported consumption.

Meat vs non-meat products

This is an area of some debate, however it is generally recognised that meat has relatively high embedded water per kilogram compared to cereals. One estimate is that to produce one kilogram of wheat an estimated 1000 litres of water is used compared to 16000 litres of water to produce one kilogram of beef (Chapagain and Hoekstra 2004).

Water used in agricultural production

At a global level agriculture is a large abstractor of water. It is estimated that global water use for agricultural production amounts to around 6390 billion cubic metres per year, including irrigation and soil water (Chapagain and Hoekstra 2004). This equates to more than 200,000,000 litres of water per second to grow food.

WWF-UK estimate that agricultural products account for 73% of the UK's water footprint, industrial products 24% and household water use 3%. (UK water footprint, Chapagain and Orr 2008)

Rice is the largest user of water out of any crops traded internationally. The global annual production of rice is estimated to accounts for about 21% of the total volume of water used for crop production, followed by wheat with around 12% of global crop water use.

Of all the crops produces globally around 15% are irrigation fed, the rest rely on natural rainfall. However, 70% of the global freshwater withdrawals are for irrigation, putting great demand on water resources. The Food and Agricultural Organisation (FAO) predicts that irrigation will play an ever growing role in global food production in coming decades.

In developed nations industry accounts for the majority of freshwater withdrawals. (See ‘Water in the supply chain’ factsheet) UK agriculture accounts for about 3-15% of freshwater abstraction according to the Environment Agency and FAO.