the environment, polluting the water of downstream users, is not. As water travels through the hydrological system from the moun- tain summit to the sea, the activities of human society capture, divert and extract, treat and reuse water to sustain communities and economies throughout the watershed (agricultural, industrial and municipal) (figure 4). These activities, do not, however return the water they extract in the same condition. A staggering 80–90 per cent of all wastewater generated in developing countries is dis- charged directly into surface water bodies (UN Water, 2008).
Unmanaged wastewater can be a source of pollution, a hazard for the health of human populations and the environment alike. The Millennium Ecosystem Assessment (MA, 2005) reported that 60 per cent of global ecosystem services are being degraded or used unsustainably, and highlighted the inextricable links be- tween ecosystem integrity and human health and wellbeing.
Wastewater can be contaminated with a myriad of different components (figure 5): pathogens, organic compounds, syn- thetic chemicals, nutrients, organic matter and heavy metals. They are either in solution or as particulate matter and are car- ried along in the water from different sources and affect water quality. These components can have (bio-) cumulative, persis- tent and synergistic characteristics affecting ecosystem health and function, food production, human health and wellbeing, and undermining human security. Over 70 percent of the wa- ter has been used in other productive activities before entering urban areas (Appelgren, 2004; Pimentel and Pimentel, 2008). Wastewater management must address not only the urban but also the rural context through sound and integrated ecosystem- based management including, for example fisheries, forestry and agriculture.
The quality of water is important for the well-being of the envi- ronment, society and the economy. There are however ways to become more efficient and reduce our water footprint. Improv- ing water and sanitation services and managing water require
investment. It is not a question of the quantity of investment. There are numerous anecdotes pointing to a history of one-off, short-term, single-sector investments – capital treatment-plant developments which were unable to secure operation and man- agement funding, built at the wrong scale or in the wrong loca- tion. Even without empirical data, it is clear that this approach is not generating results in either improved water quality or fi- nancial incentive.
A paradigm shift is required towards new approaches that in- clude wise investments and technological innovation, not one size fits all, but now ensuring that investments are appropri- ate to the industries and communities they serve. Such invest- ments can boost economies, increase labour productivity and reduce poverty. This report uses a number of case studies to il- lustrate the challenges of wastewater management, but also the opportunities for how wastewater management and reuse can safely meet the growing demands for water resources, without degrading the environment, and the ecosystem services on which we depend.
Figure 3: 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.