[[File:Susana logo.png|right|90px|Susana logo.png]]This article is based on a [http://www.susana.org/en/resources/library/details/98 factsheet] that deals with the planning of sustainable sanitation for urban and peri-urban areas of developing countries and its importance for achieving comprehensive and inclusive sanitation coverage in cities.
=== 1. Summary ===
Groundwater quality and sanitation are often linked as pollution of groundwater from unsafe household sanitation systems through nutrients, pathogens and organic micropollutants (including emerging contaminants) can occur.
Failure to improve general sanitation conditions and thereby contaminating groundwater endangers the economic growth potential of a region. This may impact negatively on the overall economic output due to increasing costs in the health, labour and production sectors. Sanitation and groundwater issues including capacity development need to be addressed on all political levels of government.
=== 2. Why care about groundwater ===
[[File:Well, Lusaka.jpg|thumb|right|200px|Well, Lusaka.jpg]]Compared to surface water bodies, groundwater resources are better protected against pollution and evaporation during dry seasons, therefore they represent a more important and efficient form of water storage. Furthermore, the development costs are usually comparatively low; as groundwater is a local resource which normally needs only simple water treatment and for small systems requires only very simple distribution systems. Natural groundwater, unaffected by human activities, is free of pathogens and in many areas free of undesirable chemical substances.
In arid and semi-arid countries groundwater is very often the sole resource for agricultural irrigation. All these facts turn groundwater in most areas of the world into an affordable, reliable and an inevitable key element of sustainable human development.
=== 3. Introduction to groundwater pollution ===
Historically it was widely believed that groundwater is generally pure and safe for drinking purposes even without treatment. However, in the past few decades, cases of disease outbreaks due to the consumption of untreated, contaminated groundwater have increasingly been reported.
The main task of a sanitation system is to contain and sanitise human excreta which contain pathogens in order to prevent the spread of diseases. A sanitation system consists of more than toilets and pits dug in the ground to collect excreta and effluents. It comprises the whole chain of household facilities, collection, transport, treatment and final destination (either disposal or reuse). Each of these components has the potential to cause pollution to the groundwater. In dealing with pollution generated by sanitation systems, the following pollutants are of importance: pathogens, chemicals and organic micropollutants.
=== 4. Pathogenic pollution ===
Pathogens cause diseases such as cholera, hepatitis A and diarrhoea. In those countries where groundwater is the sole source of drinking water, prevention of faecal-oral transmission should be a highly prioritised public health outcome. Once pathogens have infiltrated into the groundwater it takes different amounts of time for different types of pathogens to die off. During this time, groundwater travels a certain distance depending on the permeability of the aquifer (i.e. the groundwater body). In addition to natural die-off, pathogen removal is also a result of adsorption and filtration through the soil and sub-surface media.
It must be noted that it requires professional experience and knowledge of the subsurface conditions to estimate the minimum distance in the soil aquifer system, which results in a travel time of 50 days. If there is doubt, always use a conservative estimate and account for larger distances.
=== 5. Chemical pollution ===
[[File:Cl DOC.jpg|thumb|right|200px|Cl DOC.jpg]]Beside pathogens, human excreta contain organic matter, nitrogen and phosphorus. Urban wastewater has a high organic content (Figure 2), which is relatively easily oxidised under aerobic conditions. Where the water table is deep, oxygen and micro-organisms in the unsaturated zone of the aquifer may remove (degrade) much of the organic matter.
In some settings, due to the infiltration of wastewater, toxic compounds like arsenic are released. Of the various routes of exposure to arsenic, drinking water probably poses the greatest threat to human health. The International Agency for Research on Cancer (IARC) has classified arsenic as a Group 1 human carcinogen.<br/>Serious and long lasting groundwater contamination is known to result from chemical substances like chlorinated, hydrocarbons, BTEX, polycyclic aromated hydrocarbons (PAH), which are often introduced via leakages or spillage events. Where such industry chemicals are discharged into the wastewater, the drainage system is providing an additional entrance pathway to groundwater.
=== 6. Pollution due to organic micro pollutants ===
Organic micropollutants or so called “emerging contaminants” are now frequently being detected in wastewater and the environment in concentrations up to several μg/L, although they might have been present already for decades (Ternes, 2009). Prominent examples of emerging contaminants are pharmaceuticals, estrogens, ingredients of personal care products, biocides, flame retardants, benzothiazoles, benzotriazoles or perfluorinated compounds (PFC). Organic micropollutants are usually quite small (molecular weight predominantly varies between 50 and 1000 Da), therefore regular municipal WWTPs or on-site sanitation systems do not remove these polar persistent organic pollutants.
Adverse effects by individual emerging contaminants, like “feminisation” of fish, can occur down to a few ng/L, as reported for 17α-ethinylestradiol and tributyltin. Besides endocrine disrupters, pharmaceuticals (such as carbamazepine, diclofenac, fluoxetine, propranolol) have been shown to cause effects at environmentally relevant concentrations. Current research is providing a growing list of “predicted no-effect-concentrations” (PNEC) which constitute the lowest concentration where a specific emerging pollutant was observed to have an effect on any organism.
=== 7. Protecting groundwater from pollution ===
[[File:Protection areas.jpg|thumb|right|200px|Protection areas.jpg]]<span style="line-height: 20.7999992370605px"></span>The difference between groundwater resources as a whole and the source of groundwater for use can be explained through its management: When groundwater is well managed, the resource as a whole is protected for current and future uses; while we protect a currently used groundwater source in a defined area with specific and often very specific measures regarding land use.
From the groundwater resource protection point of view, the catchment needs to provide a recharge area which is part of the ecosystem mosaic and free of human activities. Ideally, the area in which humans consume water for domestic and industrial use should be situated downstream of the recharge area while agricultural activities may lie even further downstream, allowing for use of nutrients from domestic water and sanitation.
=== 8. Productive land use and groundwater protection ===
[[File:Water flux catchment zone.jpg|thumb|right|200px|Water flux catchment zone.jpg]]If a given area for agricultural production is to be used most efficiently, crop harvests need to be increased by fertiliser application. Local conditions limit the maximum amount of fertiliser that can be applied. This is determined by plant uptake depending on the crop specimen and by effective field capacity depending on the soil type. Fertiliser application exceeding this amount will cause a leaching to the groundwater. Poor timing and inappropriate dosing of fertiliser or application on sandy soil may cause leaching of nitrates into the groundwater.
Most synthetic fertilisers consist of a combination of phosphorus (P), nitrogen (N) and potassium (K). While phosphorus and potassium are prone to sorption processes in the soil, nitrogen reaches the groundwater at the same time as the percolating water. Therefore, in order to prevent high nitrate concentrations in groundwater over the longer term and eutrophication of surface waters, regulations on fertiliser application should be developed and enforced. Organic fertiliser, which produces less leakage of nitrate into the groundwater (UBA, 2002) is preferred over synthetic fertiliser, and soil should be managed in a sustainable way. Erosion, leakages of nutrients and loss of humus should be avoided.
=== 9. Policy recommendations ===
[[File:Open drain,senegal.jpg|thumb|right|200px|Open drain,senegal.jpg]] The following recommendations were developed by the participants of the international symposium “Coupling groundwater protection and sustainable sanitation” which took place in Hannover, Germany in 2008 (BGR, 2008).
*Efficient political structures, policies and legal arrangements are essential. This includes developing curricula (focussing on groundwater and sanitation) for educational systems as well as capacity building programmes. Neglecting the improvement of general sanitation conditions and thereby contaminating groundwater endangers economic output due to increasing costs in the health, labour and production sector. Sanitation and groundwater issues including capacity development have to be addressed on all political levels.
=== 10. Acknowledgements ===
SuSanA factsheet: Sustainable sanitation and groundwater protection. April 2012. [http://susana.org susana.org]
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