the population will not be economically active and hence will be more reliant on the services of those who are economically active. In addition, there will be increasing reliance on PCPPs (personal care and pharmaceutical products) that include a wide range of complex synthetic substances that may be persistent, accumulative and toxic if these enter environmental systems via toilet flushing (Kolpin et al., 2002). These and other xenobiotics may impact SO significantly on rivers in developed countries that new and more advanced wastewater treatment systems will need to be installed. However, on the positive side, the older population may have more wealth which conceivably could be invested in utilities. By contrast the developing world's population will continue to increase significantly but at a declining rate that is not expected to peak until after 2050. Six countries are expected to account for at least half of the projected increase: the Indian sub- continent of India, Pakistan, Bangladesh; then China, Nigeria and Indonesia. Although the median age in developing countries is likely to increase, it is still substantially lower than in the developed countries; currently it is around 25 and will rise to 33 by 2030. The implication is that this will create a substantial increase in the numbers of the economically active workforce. 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 Almost all the population growth in developing countries will be accounted for by urban growth - as was much the case in Europe in the 19th century during its period of industrialisation. Urban growth will be driven by inward migration from rural areas as agriculture becomes more commercialised and there is less scope for family-based subsistence agriculture. This migration will be attracted by jobs and services in urban areas, and there will also be increases in the local urban population from tho