be impossible for a government utility to do so without being seen to sanction the presence of these settlements (see Box 4).
Accessing new (non-traditional) sources of water One of the most common approaches to resolving water- supply problems is to build a large dam. Constructing them typically involves significant cost, the dislocation of many people and many adverse environmental problems.10
Schreiner et al. (2010) observe that
urban communities have historically relied on large dams for their water supplies. More recently, however, water-supply options have expanded to include the capture and storage of stormwater and desalination, fog interceptions in cloud forests (notably in the Andes mountains), transfers between islands, inter-basin water transfers, bulk transport such as by pipeline or Medusa bags (giant polyfibre bags holding up to 1.5 billion litres of potable water that are towed by ships). Other communities and countries are investing in sewage recycling. Singapore, for example, has invested in the development of systems that treat sewage to a standard allowing it to be used for drinking purposes. Most of these technologies, however, are reliant upon the use of increasing amounts of energy and, as a result, the costs of water provision are rising in most regions where there is physical water scarcity.
Desalination has the advantage that it is climate independent but, as with most of these alternative sources of supply, is disadvantaged by the fact that it requires access to large amounts of energy. Usually, sewage recycling is cheaper than desalination as it uses the same reverse osmosis technology, but requires about half as much energy per unit of water treated (Côté et al. 2005). Public opposition to household use of recycled sewage water, however, is strong (Dolnicar and Schäfer 2006). A careful assessment of the costs of these alternative sources
10. For an authoritative response to the controversies surrounding large dams, see World Commission on Dams (2000).
of supply often reveals that it is cheaper to invest in demand control (Beato and Vives 2010; 2030 Water Working Group 2010). In a green economy, there is much more attention to the long-term costs and impacts of resource use on the environment.
Producing more food and energy with less water As the world’s population increases, more water will be needed for household and industrial purposes with the consequence that in many areas, either more food will have to be imported, or more food produced with less water. When asked, “Is there enough land, water, and human capacity to produce food for a growing population over the next 50 years – or will we ‘run out’ of water?”, analysis undertaken by the International Water Management Institute (IWMI) reveals that, that “It is possible to produce the food – but it is probable that today’s food production and environmental trends, if continued, will lead to crises in many parts of the world” (Molden 2007).
For example, in many developing countries, typical irrigated maize yields are in the vicinity of one to three tonnes per
hectare, whilst they could be as
high as eight tonnes per hectare. There is a significant opportunity to increase crop yields and avoid a global food security crisis. If this opportunity is realised, then not only will it also be possible to divert water to other uses, but it will also be possible for developing countries to produce a surplus for sale to others.
Institutional reform When coupled with more traditional hard approaches
to investment in built infrastructure, the softer approach of developing more effective administrative arrangements and policies that encourage private investment can significantly reduce the amount of money that governments need to invest in the water sector to achieve the same outcome. Opportunities of how to do this are developed in section 5. Typically, soft approaches focus on incentives and the factors that motivate consumers to manage their water use.