The ratio of treated to untreated wastewater reaching water bodies for 10 regions. An estimated 90 per cent of all wastewa- ter in developing countries is discharged untreated directly into rivers, lakes or the oceans (UN Water, 2008).

The significance of wastewater and contents of wastewater vary greatly between and even within regions. In Africa for example, it is the impact on people’s health that is the major factor, in Europe, the input of nutrients into the coastal waters reducing productivity and creating anoxic dead zones.

The contaminants in waste- water come from many different sources and can have cumulative and synergistic effects requiring a multi-pronged response.

Regional variation in water withdrawal per capita and its use by sector.

Desalination is an increasingly important practice to secure clean water in a number of countries. Monitoring is key to minimize negative impacts on the ecosystem.

What one litre of wastewater might contain in terms of pathogens.

Increasing water scarcity with population increase.

Population by region was calculated averaging the results forecasted by the scenarios of the GEO-4 report using the WaterGAP modeling.

Is reuse of wastewater a benefit or a threat for agri- culture?

Case study to compare two urban centres.

Access to improved sanitation remains a pressing issue in many regions.

As water is extracted and used along the supply chain, both the quality and quantity of water is reduced.

Distribution of causes of death among children un- der five years and within the neonatal period, 2004 (Figure from WHO, 2008).

Looking at the costs and benefits, centralized systems may not be the answer in terms of best result for the investment. The chart on the left shows that the financial NPV does not change with increasing population size for centralized sewage and wastewater connection, however the economic NPV (which includes benefits to health and the environment) shows a positive trend with increas- ing populations. Centralized systems therefore generate a grea...

Water is the life force of our planet, but only 1 per cent of all the freshwater on Earth is available for human use.

The volume of water required to produce different food products varies enourmously, as do the waste products.

The world’s water resources will not change, but the human population and its demands on supply are growing rap- idly. Meeting these demands will require wise investment in how we use and reuse our water (UN Water Statistics).

Investment to improve basic access to a safe water source and sanitation (WHO scenario A) can have a significant return with the largest impact on health in particular averting diarrhoea cases and time saved (increasing productivity). Urbanized areas provide a large proportion of GDP, therefore the future development of developing countries is dependent on the productivity of growing urban areas.

Child mortality rates by cause and region, 2004. Source: WHO, 2008.

Production of red meat has a significant demand on water with impacts on quality.