Water, Sanitation and Urbanisation

Urbanisation is one of the most important demographic trends of our time. In 2008, the number of people living in urban centres worldwide has for the first time surpassed the number of people living in rural areas. It is estimated that by 2050, the percentage of urban population will reach nearly 70% (BIRCH et al. 2012).

Four main factors are responsible for urban growth: a) the natural demographic growth of urban populations, b) the absorption of rural settlements located at the edges of expanding cities, c) the transformation of rural towns into urban centres and d) migratory movements from rural areas to cities.

Urbanisation represents a challenge for water and sanitation management in developed as well as in developing countries. While cities in developed countries often struggle with high operation and maintenance costs and the decay of existing infrastructure, rapid urban growth in the developing world is seriously outstripping the capacity of most cities to provide adequate services for their citizens (COHEN 2006). In rapidly growing urban slums where there is no planning and few facilities, the number of people living without access to basic water and sanitation services is still increasing. This is of particular concern considering that the WASH sector represents the foundation on which broader goals of poverty reduction, environmental sustainability, social development, and gender equality must be built (BIRCH et al. 2012) (see also access to water and sanitation and water sanitation and development).

Conventional urban water supply and sanitation management is generally characterised by an unsustainable use of water and nutrients. This represents important environmental, economic and social challenges, which are intensified by the process of urbanisation.

• Disruption of the natural water cycle: The conventional urban water cycle is characterised by a linear infrastructure that transportsclean water into and wastewater out of urban neighbourhoods. Due to a high percentage of sealed soil and thus impervious surfaces, evapotranspiration and groundwater recharge are reduced and low quality surface runoff is increased – utilities are often left to deal with extremely large volumes of water, especially during wet weather (CORCORAN et al. 2010). Climate change will further intensify these challenges in many regions as it will lead to more erratic patterns of droughts and storms.
• Pollution of water sources: Urban settlements are the main source of point source pollution (UNESCO et al. 2004). It is estimated that more than 90% of sewage in the developing world is discharged directly into rivers, lakes, and coastal waters without treatment of any kind (LUETHI et al. 2009). In low- and middle-income countries, leaking on-site sanitation facilities together with the absence of sewerage pipes that dispose the wastewater, result in large volumes of local wastewater soaking into the soil, and eventually seeping into aquifers and polluting groundwater (GROENWALL et al. 2010).
• Depletion of groundwater sources: In urban settings, the use of shallow groundwater sources is an especially common feature of many low-income communities in low- and middle-income countries. More than half of the world’s megacities depend on groundwater (see also sources of groundwater).
• Broken nutrient cycles and impoverished soils: The “end-of-pipe” paradigm discourages recovery and reuse so that nutrients are lost to water bodies. This waste of valuable resources can lead to eutrophication and cause algal blooms and a depletion of oxygen in receiving water bodies (HOWE et al. 2011, see also sanitation systems). In Africa, 85% of arable land is losing an average of 30kg of nutrients per hectare per year (LUETHI et al. 2009).
• Waste of resources: Water treated to potable water is used for non-potable purposes such as toilet flushing, garden use and industry. When water is heavily invalid link or charged based on a fixed rate, users have little financial incentive to use it sparingly (HOWE et al. 2011).
• High water demand: The concentration of a great quantity of population and activities on a small area involve the need of a great amount of good quality water (CHOCAT 2002). Urban areas usually have a higher per capita consumption of water compared to rural areas. Water demand is additionally increased as urban population grows and per capita water consumption in many cities is on the rise (see also water use).
• Cost-intensive infrastructure for water supply and wastewater collection: The increase of urban population asks for a continuous expansion of water networks and wastewater networks (see also wastewater collection and treatment). Centralised networks are very cost-intensive in terms of construction, operation and maintenance. If the networks are not sufficiently maintained, leakages lead to a loss of valuable resources, unreliable or irregular water supply and low revenue collection for the utilities (see also leakage control). Many large cities suffer from chronic water shortages due to over-exploitation of raw water resources, and to losses of water, which sometimes reach up to 60% of the volume of water supplied (UNESCO et al. 2004).

Apart from the general challenges of water supply and sanitation in the context of urbanisation, which have been described above, developing countries are often confronted with an additional challenge: the rapid growth of slum settlements (also referred to as “peri-urban areas” as they are often located at the peripheries of the cities, e.g. favelas in Brazil or townships in South Africa). Data suggests that in a large number of the world’s poorest countries, the proportion of urban poor is increasing faster than the overall rate of urban population growth. An estimated 72 % of the urban population of Africa now live in slums. The proportion is 43 percent for Asia and the Pacific, 32 percent for Latin America, and 30 percent for the Middle East and Northern Africa (COHEN 2006).

Characteristics of Slum Settlements 

• The unplanned (informal) character of the settlements: Informal settlements (also called squatter settlements or shanty towns) are (sometimes illegal) settlements, which have emerged in the course of rapid urbanisation, unguided by urban planning. Irregular layout and spontaneous construction make the subsequent expansion of networks into densely populated areas extremely difficult.
• High population density: As population density is commonly extremely high, there is not much space left for the construction of water, sanitation and treatment facilities or network expansions.
• Low tenure security: Because informal settlements lack land tenure, providing water and sanitation services through investments in large infrastructure is extremely difficult (CORCORAN et al. 2010). In some cases, utilities are not allowed to expand their services to illegal settlements.
• Low-income areas: Slum settlements are characterised by high poverty rates. People are therefore often not able to pay for network expansion and improved service delivery.
• The relative distance to existing networks, particularly of slums located at the peripheries of the cities, makes network expansion very costly.

Water Supply and Sanitation in Slum Settlements

Although efforts to achieve universal water access have been underway for decades (see also the right to water and sanitation and water sanitation and development), the number of people living without access to basic water and sanitation services is still increasing. One main reason for this is the rapid expansion of urban slums where the characteristics described above make the provision of basic infrastructure extremely difficult. Urban slums therefore generally lack improved water supply and sanitation facilities and other infrastructure such as roads, electricity and solid wastecollection.

In order to cover their needs with respect to water supply, the peri-urban poor often depend on a variety and combination of means such as hand dug wells, boreholes, water vendors, rainwater harvesting, privately operated wells and human-powered distribution or motorised distribution, gifts from neighbours, informal operators or clandestine connections. The sources that are used vary according to their availability and accessibility and to the intended use.

Pit latrines are commonsanitation facilities in urban slums. However, in many cases even such basic means are lacking and people are forced to practice open defecation or dispose of their excreta in plastic bags which they throw on the roofs or at the street (so-called “flying toilets”).

Consequences of the lack of water supply and sanitation services

• Pollution of water sources: Due to a lack of space, pit latrines are often constructed close to groundwater sources such as wells, hand pumps or springs. During heavy rains, the latrines tend to get flooded, resulting in water seeping through the soil, contaminating the groundwater. Additionally, asthe impervious and unvegetated ground of slum areas has little or no retention during heavy rains, human and animal wastes are flushed into the river systems polluting urban water supplies, rivers and productive coastal waters (MAFUTA et al. 2011).
• Health: Approximately 80% of all diseases and 25% of all deaths in developing countries are caused by polluted water and insufficient water supply, sanitation and hygiene (LUETHI et al. 2009). This situation is particularly accentuated in urban slums where access rates to WASH services are typically very low. Among the most common diseases are diarrhoea, cholera, malaria, dysentery, schistosomiasis, dengue fever, typhoid fever, gastroenteritis, hepatitis A and cancer. Diarrhoeal diseases pose a serious risk of malnutrition.
• Poverty [Adapted from NORSTROEM 2007]: Adults who are ill themselves or who need to take care of their children are less productive. Additionally, the health costs induced by the lack of adequate water, sanitation and hygiene practices can consume a large part of the poor household’s income. The time spent to fetch water cannot be invested into income-generating activities (see also water sanitation and development).
• Education and Gender [Adapted from BIRCH et al. 2012]: While the process of urbanisation critically reduces the average time spent by women collecting water when compared to their rural counterparts, the increased risk of contracting water-borne diseases as the primary handlers of contaminated water, the serious challenge to reproductive health presented by a lack of clean water and hygiene services, and the added responsibility of providing care to children and other family members suffering from illness continue to effectively exclude many women and girls from educational opportunities.
• Dignity and Security: Due to the lack of adequate sanitation facilities, many people living in urban slums are forced to defecate in the open. In order to preserve their dignity, they often try to defecate in the open under cover of darkness. This poses an important security risk, particularly for women and girls. This risk is also given if water needs to be fetched during the night.
• Economic costs: Illnesses, high rates of mortality and reduced productivity induce large economic costs. It is estimated that Sub-Saharan Africa loses around 5 per cent of Gross Domestic Product (GDP) due to ill-health because of poor water and sanitation – more than the total value of aid these countries receive (TEARFUND 2008). Studies have shown that investments in sustainable sanitation in developing regions brings a return in the range of US$5 to US$46 (depending on the intervention) for every US$1 invested (LUETHI et al. 2009).

Although urban areas present major challenges for adequate water and sanitation management, “they also present a potential efficiency of scale in basic service provision never possible in the rural context. Urban systems also present the best opportunity for a transition to integrated service management, leveraginginvestments in energy, transportation, water, and sanitation in order to create more innovative and environmentally sustainable human development and natural resource management” (BIRCH et al. 2012). In order to achieve urban sustainable sanitation and water management, the following aspects should be considered (see also case studies on Urban SSWM).

• Integrated approach: The conventional urban water cycle is fragmented into different sectors (water purification and water distribution, wastewater and stormwater). This may lead to missed opportunities and unexpected impacts. A governance andinstitutional change is therefore needed, which looks at water supply and sanitation systems in a holistic way. An integrated approach (including the different aspects of urban water management (see also water safety plans or city sanitation plans) and also other affected urban management sectors such as health, housing, energy or waste management) to urban water management makes it easier to identify and exploit positive links while minimising the negative implications throughout the system (HOWE et al. 2011).
• invalid link: Centralised systems of water and sanitation services as they exist in most cities of the developed world are proving not to be effective and efficient. Furthermore, they are very expensive. It does therefore not seem logical to use these systems in developing countries (CHOCAT 2002). Decentralised water supply and wastewater treatment systems offer increased opportunities for local stakeholder participation in planning and decision-making (see also the role of local governments in urban sustainable sanitation and water management), and for reutilisation of the resource at the local level (PARKINSON and TAYLER 2003) and should therefore be encouraged.
• Particularly in developing countries, public service providers are often unable to keep up with urban population growth as they face a double challenge of maintaining the existing and often deteriorated networks and of extending the services to the rapidly growing settlements at the peripheries of the cities. Through the engagement of the private sector (see e.g. invalid link or invalid link), service delivery can be improved as public utilities are relieved and additional revenue opportunities are created.
• invalid link resulting from sustainable sanitation and water management can include small-scale service provision for construction of appropriate system components, collection, transport, storage and processing/recovery of products from sanitation systems (e.g. biogas, fertiliser, soil conditioner or irrigation water), resources management (dealing with resources that are scarce in the local context and evaluating how a sanitation system can reduce resource pressure), surveys, analyses, and impact evaluation (e.g. market surveys, institutional analysis, impact evaluation of previous sanitation strategies, and sustainability assessments) (LUETHI et al. 2009) (see also Sanitation as a Business).

• Reuse opportunities: In the conventional urban water cycle, reuse opportunities remain largely unused, leading to a waste of valuable resources. Sustainable urban water and sanitation management takes advantage of the reuse options including the reuse of energy from wastewater through biogas, the reuse of wastewater and greywater for irrigation as well as the reuse of nutrients from human urine and excreta to recover nutrients and limited resources like phosphorus for agriculture.
• Financial sustainability: If water supply and sanitation solutions are to be sustainable, they need to remain operative over time. This requires sufficiently high investments in the water sector and sound financial planning.
• Stakeholder engagement (see also participatory decision making): Urban areas provide an ideal institutional structure for community engagement. Increased stakeholder engagement leads to better identification of challenges, demand-driven solutions and better commitment and ownership and thus to a more significant impact (see e.g. community-led urban environmental sanitation).