l as a way of reducing operational costs in the long term. As well as recovering energy at sources such as reservoirs and other storage sites, possibilities include turbines in water transmission and distribution systems and in sewers, and energy from solid residuals from treatment processes. There are now several operational examples of the first of these and the latter has been common for sludge from activated sludge plants for decades, but is still often not utilised due to capital and running cost fears. In a similar way that concerns over Y2K led to developments in software and electronic systems, SO threats of terrorism and cyber crime would lead to INFRASTRUCTURE TO 2030: TELECOM, LAND TRANSPORT, WATER AND ELECTRICITY - ISBN 92-64-02398-4 © OECD 2006 5. THE IMPACTS OF CHANGE ON THE LONG-TERM FUTURE DEMAND FOR WATER SECTOR INFRASTRUCTURE investment in improving the robustness of these systems. Such developments would not come specifically from the water sector; rather, the sector could draw on the advances made in other business areas, especially with respect to communications, databases and control systems. In terms of the possible impact on funding and investment it is expected that much of the cost would be absorbed within existing budgets and would not give rise to additional programmes of work requiring special funding streams, although it may facilitate access to military spending sources. These developments could be widely adopted across all but basic service provision, such as for rural water services. Macroeconomy Economic growth World income will continue to grow, rising by 3.1% p.a. to USD 51 800 billion in 2015, with world per capita income also rising but significantly faster than in the past three decades (World Bank, 2005). Also, the income gap between developed and developing countries should shrink given the differences in their rates of growth, with the fastest growth taking place in East and South Asia. This continued economic growth will require substantial upgrading of infrastructure if