How much water did it take to make your jeans

When we talk about water consumption, we immediately think about drinking, bathing, watering plants, cooking and washing.

Those of us with the privilege of having our names on monthly water bills are told clearly how much water has been consumed by the household and how that figure stacks against an average household of similar size.

However, this is not our total water consumption. In fact, globally the water consumption due to household water use accounts for only 8 per cent of total water demand. The rest is used in industries and agriculture. Given that the purpose of industry and agriculture is to produce goods and services that are eventually consumed by us, placing a water tag on them might provide a true measure of the water consumption by an individual or a nation.

The concept of virtual water was coined by Professor John Allan (2008 Stockholm Water Prize Laureate), which refers to the volumes of water required to produce the various goods and services in industries and agriculture.

The table shows the amount of water consumed to produce a list of products.

The value of imposing a water tag on goods consumed could help create awareness of the amount of water that is being used in the production of various goods and the amount of water that an individual, region or nation is consuming. This could potentially lead to optimisation of water use in the production of these goods and also help countries/regions with water scarcity to decide effectively what goods should be produced and what should be imported.

For example, a water scarce country might find it more favourable to import jeans to meet the local demand as opposed to producing the jeans itself. This way it can save tonnes of water. For the consideration to work however, the scarcity of water has to be priced into the value of water, when compared against land, labour, energy and other economic considerations.

With a water tag on goods and services, it is then possible to calculate the total water footprint of an individual or country. This measure is being championed by the Water Footprint Network (WFN) to become a global standard for the measurement of water consumption. According to data collected by WFN, although the total water footprint for China, India and the United States together accounts for 39 per cent of the global water footprint, the water footprint per capita in China and India is less than half that of the US and other affluent countries due to higher consumption.

The percentage of a country's water footprint that falls outside it is another useful parameter. In the case of India it is less than 3 per cent, but Singapore, without any natural resources, is estimated at 90 per cent. Therefore countries with sufficient water resources to meet their water footprints should manage them efficiently. And countries with insufficient water resources should strive to increase these resources by adopting technology for recycling/desalination or importing water intensive products.

All should strive to reduce consumption of goods.

Therefore the next time you decide what to consume or discard, do consider its water tag and how every decision you make helps to lessen the dependency on water in your country and globally.

Dr Gurdev Singh is head of water technology at the Environmental & Water Technology Centre of Innovation in Ngee Ann Polytechnic

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