2. Water & carbon footprints
• Carbon footprint is the total • Water footprint is the total
mass of GHG that is emitted volume of freshwater that is
to produce the goods and used to produce the goods
services expressed as and services expressed as
carbon dioxide equivalent m 3.
4. All food contains “embedded”
or “virtual water”
water for drinking, cleaning, etc.
Water for plant growth
5. 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
Water Tea • Sugar 8 g
9.2 lt to grow the cane
Milk
• Total 32.4 litres
Ignores all the water used in manufacturing the cup, processing the tea, milk and
sugar, producing electricity for the kettle and washing up!
6. If you think that’s a lot ……
Embedded or virtual water
200
180
ater content, litres
160
140
120
100
80
Virtual w
60
40
20
0
Cup of tea Glass of Cup of Pint of Glass of
wine coffee beer milk
After Hoekstra & Chapagain (2007)
7. 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 900
Hoekstra & Chapagain, 2007
8. How much water do we eat?
Basic survival 1000
Acceptable
3500
nutritional diet
Californian diet 5500
UK Domestic water
153
consumption
0 1000 2000 3000 4000 5000 6000
litres/ person/ day
9. Processing
Rainwater Steam
430 mil l/d
Mains water
Outputs
Inputs
Waste water
Recycling
Rivers
& Groundwater
260 mil l/d Food & drink industry (UK)
After Defra (2007)
10. Growing potatoes in
E. England
Water to grow
130 l/kg
the potatoes
Water used in
10 l/kg
processing
Water used in
0.1 l/kg
the home
11. Britain’s agricultural water footprint
• Total agricultural water footprint 74.8 Gm3/yr
30% of all the rain that falls on the UK
3,400 litres / person / day
Domestic water use = 153 litres / person/ day
• 60% crops, 40% livestock
• Internal = 28.4 Gm3/yr
• External = 46.4 Gm3/yr
Source: Chapagain & Orr (2008)
13. The colour of water
Water used at the point
Green Water where rain falls
Water abstracted from rivers,
Blue Water lakes and groundwater
Water required to dilute
Grey Water polluted return flows
14. 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
15. Colour is important
250 g Peanut M&M’s ® 575 g Dolmio® pasta sauce
1,153 litres 202 litres
Blue 127 128
Green 987 21
Grey 39 53
Based on production in Australia – Source: Ridoutt et al., 2009. J. Cleaner Production
16. Blue water abstraction in the UK
• Total water use 500 mil m3/year
• Equivalent to domestic consumption of
9 million people
Livestock
23%
Food & Drink
Industry
50%
Agricultural
Irrigation
27%
17. 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
18. Water availability
Water available
No water available
Over licensed
Over abstracted
19. 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
20. 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
21. 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)
22. 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
23. 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
