Water Footprints 5 March 2009 Tim Hess Cranfield University

Water & carbon footprints

• Carbon footprint is the total mass of GHG that is emitted to produce the goods and services expressed as carbon dioxide equivalent

• Water footprint is the total volume of freshwater that is used to produce the goods and services expressed as m3.

Water footprint of food

Production

Processing

Consumption

All food contains “embedded” or “virtual water”

Water for plant growthWater for plant growth

water for drinking, cleaning, etc.water for drinking, cleaning, etc.

How much water does it takes to make a cup of tea?

• Hot water 0.2 lt• Tea leaves 2 g

5 lt to grow the tea

• Milk 0.02 lt 18 lt to grow the grass

• Sugar 8 g 9.2 lt to grow the cane

• Total 32.4 litresIgnores all the water used in manufacturing the cup, processing the tea, milk and sugar, producing electricity for the kettle and washing up!

Water Tea

Milk

Sugar

If you think that’s a lot ……

0

20

40

60

80

100

120

140

160

180

200

Virtu

al w

ater

con

tent

, litre

s

Cup of tea Glass ofwine

Cup ofcoffee

Pint ofbeer

Glass ofmilk

After Hoekstra & Chapagain (2007)

Embedded or virtual water

Water required to produce 1kg

litres / kg

Meat (bovine) 15 500

Meat (sheep) 6 000

Meat (poultry) 4 000

Rice (broken) 3 500

Eggs 3 300

Soybeans 1 700

Wheat 1 300

Maize 900Hoekstra & Chapagain, 2007

How much water do we eat?

153

5500

3500

1000

0 1000 2000 3000 4000 5000 6000

UK Domestic waterconsumption

Californian diet

Acceptablenutritional diet

Basic survival

litres/person/day

Processing

Rainwater Steam

Mains water

Inputs

Rivers & Groundwater

Waste water

Outputs

Recycling

After Defra (2007)

260 mil l/d

430 mil l/d

Food & drink industry (UK)

Growing potatoes in E. England

Water to grow the potatoes

Water used in processing

Water used in the home

10 l/kg

130 l/kg

0.1 l/kg

Britain’s agricultural water footprint

Source: Chapagain & Orr (2008)

• Total agricultural water footprint 74.8 Gm3/yr

30% of all the rain that falls on the UK

3,400 litres / person / dayDomestic water use = 153 litres / person/ day

• 60% crops, 40% livestock• Internal = 28.4 Gm3/yr• External = 46.4 Gm3/yr

External agricultural water footprint

0

1000

2000

3000

4000

5000

6000

7000CocoaBovineCottonSwineOil PalmSoybeansCoffeeLivestockMilkMaizeRiceW heat

The colour of water

Green WaterGreen Water Water used at the point where rain falls

Blue WaterBlue Water Water abstracted from rivers, lakes and groundwater

Grey WaterGrey Water Water required to dilute polluted return flows

Blue water / Green Water

• Green water• Opportunity cost of water is low• Opportunity cost for land may

be higher• Blue water

• Taken from renewable resources

• Competes for water with other uses

Colour is important

Based on production in Australia – Source: Ridoutt et al., 2009. J. Cleaner Production

Blue 127 128Green 987 21Grey 39 53

250 g Peanut M&M’s ®

1,153 litres575 g Dolmio® pasta sauce

202 litres

Blue water abstraction in the UK

• Total water use 500 mil m3/year• Equivalent to domestic consumption of

9 million people

Food & Drink Industry

50%

Agricultural Irrigation

27%

Livestock23%

Impact of the blue water footprint

• Not all abstraction is harmful• Water that would have no other “use”

(including environmental flows )• Water in excess of other requirements

(e.g. winter high flows)• In water stressed catchments abstraction may have

severe environmental impacts

Water availability

Water available

No water available

Over licensed

Over abstracted

Opportunities to reduce impact: Cropping

• Relocating production / abstraction to less stressed catchments (“claw-back” of licences)

• Encourage high-flow / rain water storage

• Efficient use of water on the farm • Equipment• Scheduling

• Using “appropriate” quality water

Opportunities to reduce impact: Livestock production

• Mostly for drinking, with little scope for savings.

• More prominent in the West (less stress anyway)

• Savings by reducing waste and good management practices at the farm scale

Thompson et al., 2007

Opportunities to reduce impact: Processing industry & retail

• Water efficiency, water recycling• Reduces costs of water, effluent disposal and treatment

(£300 million annual water bill for food & drink industry, Defra, 2007)

• Reduced energy requirements & CO2 footprint• Food and Drink Federation (FDF) commitment to savings

of 20% by 2020• Food waste is water waste

• Spoilage• Wastage (appearance)

Water & carbon footprints

Carbon Footprint Water Footprint

What we put in What we take out

Total mass over life-cycle Total volume over life-cycle

Doesn’t matter where it goes Matters where it comes from and where it goes

Conclusions

• Water footprints are important, i.e. the impact on the environment is important

• But it is not all about “size” - don’t assume that a big water footprint is “bad”

• Need to consider “ecosystem impact”, which will be very case specific and includes livelihoods.

• 62% of the UK’s agricultural water footprint is overseas

• Work with supply chain, processors and consumers to encourage benign water use

Water Footprints 5 March 2009 Tim Hess Cranfield University