Today, one in two people on the planet live in a city. The world’s cities are growing at an exceptional rate and urbanisation is a continuum. The main reason they are growing is because of natural increase in urban population, but also due to rural-to-urban migration and reclassification of rural areas to urban areas.
93% of the urbanization occurs in poor or developing countries, and nearly 40% of the world’s urban expansion is growing slums. Between 1990-2001 the world’s slums increased at a rate of 18 million people a year, and is projected to increase to 27 million new slum citizens per year between 2005-2020.
Investments in infrastructure have not kept up with the rate of urbanization, while water and waste services show significant underinvestment. The central problem is therefore the management of urban water and waste. Piped water coverage is declining in many settings, and the poor people get the worst services, yet paying the highest water prices.
Few urban authorities in developing countries have found a sustainable solution to urban sanitation, and utilities cannot afford to extend sewers to the slums, nor can they treat the volume of sewage already collected. Solid waste disposal is a growing threat to health and the environment.
Cities are complicated to manage: different approaches are needed for different types of urban environments. But cities also provide the best opportunity to improve livelihoods and infrastructure development, including water and waste services.
The big opportunity is increased recycling and reuse of water and wastes, an integrated urban management. Adopting more efficient water treatment technologies and capturing water and wastes within the city will also minimize environmental and downstream pollution.
50% of the world population live in cities of 10 million people or more. Africa and Asia have the highest rates of urbanization, further boosted by conflicts and disasters. Urbanization is not only centered in the rising megacities in the South, but also in the unstoppable growth in secondary cities and towns. In Latin America the majority of the population lives in smaller urban centers. Centers where we will see the biggest growth during the 20 coming years.
There is growing evidence that water resources will be significantly affected by climate change, both in quantity and quality, particularly through the impact of floods, droughts, or extreme events.
The effect of climate change will also mean more complex operations, disrupted services and increased cost for water and wastewater services. In addition, climate change and disasters will result in bigger migration to urban areas, increasing the demands on urban systems.