The growing global population is set to put an ever-increasing strain on water supplies in our cities. Peter Brabeck-Letmathe takes a look at what can be done to tackle the problem.
I recently participated in the combined Singapore International Water Week and World Cities Summit, which gave me an opportunity to reflect on the complex relationship between water and urbanisation.
Here are a few data points to provide some perspective right from the outset: the rate and quality of urbanisation are one of the key megatrends of the 20th and 21st centuries, with massive acceleration. In the 50 years prior to 2010, globally there were some 38 million additional urban dwellers per year, in the next 50 years it will be an increase of close to 70 million annually.
This acceleration in the rate of urbanisation is a huge challenge, but like many other challenges, this also means opportunity. In 2012, I organised a breakfast discussion on urbanisation at the World Economic Forum in Davos. One of the main outcomes was the common understanding that cities are nodes of new ideas, communication and innovation. This is further accentuated by the much higher share – compared to country averages – of people aged between 15 and 35. So, while there are issues, cities also generate ideas and solutions.
How does this relate to water? Cities per se do not need more water per inhabitant than, for example, a non-agricultural population living in villages. But in cities, water needs, whether direct or embedded, are highly concentrated geographically.
The buildings of a city of ten million inhabitants cover quite a surface. For example, in Seoul, South Korea, it is the equivalent of a circle with a radius of 14 kilometres, but in Kinshasa in the Democratic Republic of Congo, with less high-rise buildings, it is the equivalent to a circle with a radius of 19 kilometres.
The water requirements for municipal supply are such that this metropolitan surface, as big as it is, will not be enough to ensure full recharge by precipitation. This is only possible with a second circle of some 100-150 kilometres, depending on the climate, where all water renewed in the water cycle is at the disposition of this city. Cities like Singapore have found a way to reduce the needs significantly through a very high percentage of used water recycling. Other cities, such as Jakarta, Indonesia, and New Orleans in the US, for instance, pump water from underground aquifers without consideration of recharge. The result is subsidence, i.e., these cities sink with a rate of up to 50 centimetres per year. Needless to say that this increases the risk of flooding, much more, for instance, than climate change.
But there is another circle, i.e., the water needed to grow food to feed the city and to generate enough energy required. Just to provide an order of magnitude: while we use some 100-200 litres of tap water per capita per day in households (a few litres for drinking and cooking, much more for other purposes such as watering lawns, washing cars, etc.); we eat, depending on the diet chosen, between 3,000 and 6,000 litres of water embedded in food. With this water requirement added to all the others, you get to a circle with a radius of up to 500 kilometres with all water – directly used and embedded – mainly servicing a city of some 10 million inhabitants. For a city of one million inhabitants there is still a radius of some 150 kilometres. Draw these circles around existing cities on a map of major countries and you see the overlap, illustrating overuse and potential conflict.
How can a company such as Nestlé address these issues, and contribute to increasing both food and water security?
The first aspect: with longer distances for food supplies, a farmer with his tractor and a load of organic vegetables will be less and less able to reach consumers. A modern food industry providing preservation and packaging for the safety of products, and modern logistic and products adapted to urban consumers become essential to supply security. In addition, structures to overcome longer distances help avoid or reduce water overuse in regions close to cities.
Industry can also contribute to saving water embedded in food products. The first and probably most important way to do this is by reducing waste from farm to fork. A second one – and there are others – is to continue reducing the high amount of waste in households, e.g., through smaller portion packaging (also personalised nutrition) and better conservation.
But the main action has to come in combined efforts of stakeholders in and around watersheds, under the leadership of governments. These efforts must be relevant – not just symbolic, make-believe action of a size that is at best marginal when compared to the gap between withdrawals and sustainable supply in a watershed – and cost-effective. For example, priority must be given to those measures that reduce withdrawals at the lowest cost per cubic metre saved. This is the approach of the 2030 Water Resources Group.
The challenge of urbanisation and water availability can be solved, provided we have a clear understanding of the facts and drivers that are undistorted by ideology.