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Sanitation aims to reduce the risks of pathogen transmission from human waste. Lots of effort therefore goes into providing people with safe and convenient sanitation facilities in their homes. However, often in sanitation planning, little attention is given to what happens with the waste afterwards. This can lead to pollution through seepage from pit latrines or through disposal of wastewater into receiving water bodies. This means that pathogen transmission can still take place, but further 'down the drain'. A related issue concerns demands made upon water resources, for example, due to flushing toilets.
Water resource managers are becoming increasingly aware of these issues and are turning their attention to sanitation, especially as part of an Integrated Water Resources Management (IWRM) approach.
This Briefing Note discusses the linkages between sanitation development and water resource management, and the ways in which concerns for both can be effectively integrated and managed.
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WELL BRIEFING NOTE 19 Go BackLooking up the pipe and down the drain Positioning sanitation within Integrated Water Resource Management This Briefing Note discusses the linkages between sanitation options and water resources and the ways in which concerns for both can be effectively integrated and managed.
Compiled by: Julie Fisher of WEDC Briefing Note Source Material: Stef Smits, IRC
IWRM, Sanitation and the Water Cycle The various definitions of IWRM are all based on the principles of equity (access and benefits), efficiency (supply to the greatest number of people) and sustainability of use. The Joint Monitoring Programme (JMP) of WHO/UNICEF states that excreta disposal systems are adequate if they are private and if they separate human excreta from human contact. One of the main methods of preventing pathogen transmission therefore, is an effective disposal and removal facility for faecal matter in the home. As sanitation is an integral part of the water supply chain, safe sanitation services traditionally consider all the elements in Figure 1.
With increasing scarce water resources, using potable water to transport human waste is inefficient and wasteful. At the same time, seeing sanitation as only the removal of waste, has led to pollution of water resources. The impacts of sanitation should be key to IWRM, as part of a broader focus on the water resources it is using and polluting. This requires the water and sanitation sector to look both 'up the pipe and down the drain'. Putting Water Use for Sanitation into Perspective The water demand for sanitation depends on the type of technology used: At a global level, domestic water use accounts for only about 10-20% of total water use, with sanitation at less than 1%, compared to agriculture, which accounts for 60-80%. At the local level, however, the demand caused by sanitation can be an important part of total domestic water consumption, especially in large cities with full-flush toilets, which puts a huge strain on water resources in some regions. Even when water resources are in abundance, there are still water-saving alternatives to flush toilets:
Rainwater for school sanitation In Chacon Nuevo, a village on the Columbian Pacific coast, there is no water supply system. Few premises have toilets, but those that do have flush toilets are connected to rainwater tanks. With over 3000mm of rain per year, water resource availability is not a problem. Pollution from On-site Sanitation The type and amount of water pollution depends on the sanitation option. There are three main problems that arise: the transmission of disease-causing organisms (pathogens); oxygen depletion of receiving waters (rivers and lakes); and eutrophication through excess nutrients in receiving waters. Pit latrines The main risk posed by pit latrines is microbiological contamination of groundwater. This mainly affects only those who use water from boreholes or wells. Water resource management should cover risk assessment and alternative technologies for the specific site conditions. Sludge disposal Inappropriate sludge disposal can also pollute groundwater and open water bodies, making sludge management important. It can be disposed of on water or land (with risks of pathogen transmission), added to wastewater treatment works, or turned into agricultural compost and biogas.
Flush toilet to septic tank Similar contamination issues apply. The various management options for emptying septic tanks pose risks, requiring careful planning of treatment and/or disposal sites and awareness of potential downstream impacts.
Sewers The only direct pollution caused by sewers is if they leak, although cross contamination of piped water systems is also common. More importantly, sewerage systems collect all types of household, industrial, hospital and solid waste, resulting in a wide variety of pollutants. Wastewater treatment can be most effective when waste flows are separated and kept as homogeneous as possible.
Wastewater treatment and disposal Wastewater treatment and effluent disposal is arguably the most obvious point where sanitation and water resource management meet. Treatment and disposal options are largely determined by earlier activities in the chain, but the main objective is to remove the risks from the three main types of contaminants. Despite this, wastewater treatment occurs only to a very limited extent, mainly due to the costs of construction, operation and maintenance.
Reuse of wastewater Reuse of wastewater is emerging as an important issue relating to both pollution prevention and minimising treatment costs. A typology of wastewater use:
Van der Hoek, in Scott et al, (2004).
Wastewater treatment technologies suitable for meeting microbiological guidelines for reuse of wastewater in agriculture include the use of waste stabilisation ponds, wastewater storage and treatment reservoirs, or conventional treatment processes. A range of health protection measures including crop restriction, irrigation techniques and human exposure control should all be considered in conjunction with partial wastewater treatment. In some cases, community interventions using health promotion programmes could be considered. Sanitation in Water Resource Management The way in which sanitation is managed has an impact on water resources, while at the same time, sanitation is heavily dependent on them. The water and sanitation sector needs to manage this dual role and two strategies exist for this: to position sanitation more effectively in water resource platforms, and to apply an integrated approach within sanitation development. Both are important and their suitability depends on the case in question. Sanitation in water resource management platforms The known linkages between sanitation options and water resources require local authorities, who are responsible for sanitation, to engage with the water resource management institutions that are being established in many countries. Some cautionary lessons for these local authorities are:
An integrated approach to sanitation An alternative can be to follow an integrated approach within the sanitation sector, maintaining the sector's own mandate of equity, efficiency and sustainability. Key guiding principles should include:
Conclusions As delivery of both rural and urban sanitation services is scaled up, there is a tendency to focus only on the household level, ignoring the subsequent stages of waste management. Where there is water-borne sanitation in the growing urban centres, there is a significant impact on water resources. These linkages require those responsible to implement processes by which they can be strategically managed and any potential problems overcome.
Background Report containing full details of all the materials used in support of this Briefing Note For further information contact:
WELL Water, Engineering and Development Centre (WEDC) Loughborough University Leicestershire LE11 3TU UK Email: well@lboro.ac.uk Phone: +44 (0)1509 228304 Fax: +44 (0)1509 223970
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