2009 Water Footprint
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Transcript of 2009 Water Footprint
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