OR/15/009 Appendix

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Lapworth D J, Carter R C, Pedley S and MacDonald A M. 2015. Threats to groundwater supplies from contamination in Sierra Leone, with special reference to Ebola care facilities. British Geological Survey Internal Report, OR/15/009.
Table A1 Groundwater quality surveys in representative regions in Sub-Saharan Africa (n=51), adapted from Lapworth et al (2015)[1].
Area Geology Sample sites (n) Results from selected water quality parameters* Sampling time frame Conclusion and sources of contamination Reference
2Bombali, Sierra Leone Granitic Basement Wells (60) FC 0-80, mean 16.6
SEC 38-554
NO3 25-280
Turb, and other majors, pH <6.5 		Single study during the wet season May–June 2010 Wells contaminated with FC, 60% above. Who standards. Low pH concern for corrosion. Ibemenuga and Avoaja (2014)[2]
3Njala, Sierra Leone Granitic Basement Springs and wells (8) FC 50–39k, mean 3.2k
FS 5–2k 		Monthly Wet and dry season sampling Increased contamination during the onset of dry season and at the start of rainy season Wright (1986)[3]
3Moyamba, Sierra Leone Granitic Basement Springs and shallow wells (13) FC 15–251k
FS 12–63k, mean 501
SEC 7.6–206, mean 30
Turb, pH 5–6.5 		Transition from dry to wet season, multiple sampling occasions Increase risk during onset of wet season sustained risk during dry season for wells. No sanitation, open defecation practiced. Wright (1982)[4]
3Bo, Sierra Leone Granitic Basement Wells (33) lined and unlined FC 0–75, mean 19.6
NO3 0.5–28, mean 7.7
PO4 0.01–11.5, mean 1.7
SEC 39–1281, mean 362 		Wet season Distance from field significant predictor of FC, not distance from toilet/PL Jimmy et al. (2013)[5]
3Conakry, Guinea Volcanic rocks, fissured Wells (69) Mod.wells FC 370-1x105
FS 90-9k
NO3 2-46
NH4 0.06-7
Cl 17-130
F 0-0.16
Turb. 1-70 		Trad. wells
FC 50-2 x105
FS 150-2 x104
NO37-51
NH4 0.01-8
Cl 8-284
F 0.0.38
Turb. 1-63 		Dry season April-May 1994 Widespread contamination by nitrate and FC linked to poor sanitation and well construction Gélinas et al. (1996)[6]
2Various.
Ivory coast 		Basement Boreholes (230) NO3 mean 69 1981 and 1982 High nitrate (up to 200 mg/L) linked to domestic pollution and deforestation Faillat (1990)[7]
2Bolama City, Guinea Bissau, Sandy soils and Cenozoic–Modern sediments Wells (28) SEC 27-326, mean 136
Turb. 1-26, mean 6.5
TC 0-23000, mean 2306
FC 0-5000, mean 410
Fecal Enterococci 0-850, mean 74
NO3 0.9-55.3, mean 16.6
NH4 0.01-1.37, mean 0.11
NO2 0.03-0.13, mean 0.04
Cu, Fe, Cr, As, 		July 2006 80% of wells contaminated with FC linked to widespread use of PL Bordalo and Savva-Bordalo (2007)[8]
2Cotonou, Benin Quaternary to mid Pleistocene sandstone Dug wells in upper aquifer in densely populated area (379) SEC 320-1045
Mn 0.06-0.19
NO3 10.4-118
PO4 <0.05-21.6
SO4 3.14-86.3 		May 1991, August 1991 and April 1992 High P and K concentrations in upper aquifers linked to anthropogenic pollution Boukari et al. (1996)[9]
1Kumasi, Ghana Precambrian Basement Hand-dug wells (10) TDS 6-230, mean 113
NO3 0-0.968, mean 0.16
PO4 0.67-15, mean 7.8
TH 8-103, mean 54
TC and EC <20 		N/A Water quality survey showed that water quality parameters were within WHO drinking water guideline values Nkansah et al. (2010)[10]
3Kumasi, Ghana Precambrian Basement Borehole and wells in peri-urban communities (9) Fe 0.001-0.955
Mn 0.018-0.238
Pb 0.005-0.074
TC 3-16.8×106
FC 1.5-4.37×104
Enterococci 1.3-53.5 		Monthly between Dec 2000 and Jan 2001 Poor quality overall, contamination linked to proximity to PL and refuse tips as well as livestock Obiri-Danso et al. (2009)[11]
3Ilesha, Nigeria Basement Wells (86) Mean results: NO3 35
Cl 34
SO4 2.8 		Single survey Evidence of anthropogenic impact on water quality degradation using PCA Malomo et al. (1990)
1Benin City, Nigeria Quaternary to mid Pleistocene sandstone Boreholes and open wells (6) Pb 0.03-0.25
Zn 0.98-7.19
Cr 0.02-1.1
Cd Nd-0.23
FC 4600-240000
FS 600-35000 		Single survey Elevated Pb, Cr, Cd and Zn attributed to indiscriminate waste disposal and FC occurrence linked to PL, soak- always and septic tanks Erah and Akujieze (2002)[12]
2Calabar, Nigeria Tertiary to recent sands and gravels Existing wells (20) BOD 0.06-4.09, mean 1.72
N 0.09-3.5, mean 2.15
Cl 0.1-1, mean 0.45
FC 0.75-4.32, mean 1.86 		N/A FC, nitrate and Cl had a positive correlation with urbanisation Eni et al. (2011)[13]
1Ibadan, Nigeria Basement, banded gneiss and schist Existing wells (N/A) TSS 159-186.6, mean 174
Cl 1.1-10, mean 5
TC 2300-9200, mean 5120 		Dry season Gross pollution of groundwater attributed to poor well construction, PL and waste management Ochieng et al. (2011)[14]
2Ibogun, Pakoto, Ifo, Ogun State, Nigeria Cambrian basement geology and weathered regolith Dug wells, communities of 5000-20,000 people (20) TDS 100-2200
TH 6-246
NO3 0.8-88
TC 0-0.6 (cfu x105)
FC 0-0.2 (cfu x105)
FS 0-0.7 (cfu x105) 		July–August 2009 Water quality standards for nitrate, FC, FS not met for significant proportion of wells Adelekan (2010)[15]
1Lagos, Nigeria Alluvium over sedimentary Urban wells (18) TDS 79-1343, mean 514
TH 24-289, mean 110
Na 8-274, mean 79
NO3 0.05-1.51, mean 0.4
Pb 0-1.9, mean 1.6
Zn 0-4.2 mean 0.3 		Survey August to October 2004 Sources of contamination included sanitation, textiles, pharmaceuticals, food, tanneries, motor industry Yusuf (2007)[16]
1Surulere, Lagos, Nigeria Alluvium over sedimentary Wells and boreholes in a middle class area (49) Al 1-99 µg/L
Cd 1-98 µg/L
Pb 1-24 µg/L 		July 2009 Pb and Cd above WHO drinking water standards in >30% of sites Momodu and Anyakora (2010)[17]
1Abeokuta, Nigeria Basement igneous and metamorphic Shallow wells including sanitary survey (40) All bacterial count>20 Maximum 800 EC+PA+SAL December 2005 Shallow groundwater is highly contaminated with bacteria. Sources include pit latrines, livestock and solid waste Olabisi et al. (2008)[18]
2Abeokuta, Nigeria, urban & peri-urban Basement igneous and metamorphic Shallow wells (76) Urban
(mean) TDS 402
TH 30.3
NO3 12.02
PO4 0.21
Pb 0.25
Zn 0.12
TC 10500 		Peri-urban
(mean) TDS 263
TH 31.7
NO3 10.7
PO4 0.03
Pb 0.19
Zn 0.09
TC 10000 		Dry season Mean values for Pb, nitrate EC and TC > WHO standards. Trading, textiles, transport, cottage industries, pit latrines Generally higher in dry season Orebiyi et al. (2010)[19]
1Peri-urban area, Abeokuta, Nigeria Basement igneous and metamorphic Hand-dug wells (25) TDS 50-270, mean 163
NO3 2.97-40.7, mean 17.6
NH4 0-0.59, mean 0.11
PO4 12-86 µg/L , mean 46
TH 12-210 , mean 106 		Rainy season 2008 Direct surface run off into wells is suggested as possible contamination source Taiwo et al. (2011)[20]
1Warri River plain, Delta, Nigeria Alluvial Benin formation Boreholes near WW treatment plant TDS 16-81
COD 0.4-44.4
NO3 0.3-1.2
Fe 0.05-0.15 		2 year sampling campaign River infiltration, municipal wastewater, agriculture, oil industry Ibe and Agbamu (1999)[21]
1Warri River plain, Delta, Nigeria Quaternary and older sedimentary sequences Dug wells Fe 0.32-2.75
Pb 0.058-0.443
Ni 0.008-0.188
V 0-4
Cr 0-9
Cd 0.75-8.5
Zn 0-1.8 		N/A Pb, Ni exceed WHO standards. Sources include Warri River, settlement, refinery. Highest values in village 3 km from refinery Aremu et al. (2002)[22]
1Masaka, Nigeria Cretaceous sandstone and clay Dug wells, high density (12) TDS 528-935
NO3 44.5-92.5
Alk 67-179
Cl 41-118
Fe 0.085-0.199
Cr 0.005-0.0126
TC 25900-78400 		Samples taken in wet season WHO standards exceeded for a range of contaminants including nitrate, TDS, Cr, Cd and TC. High density settlement with shallow water table Alhassan and Ujoh (2011)[23]
2Yaounde, Cameroon Basement Springs and wells in high density area (> 40) SEC 18.2-430, mean 87
FC 60% >100
FS 5%>100 		One-off survey Groundwater’s in high density zones show significant degradation (chemical and microbiological), linked to PL Ewodo et al. (2009)[24]
2Douala, Cameroon Alluvium over Pliocene sand and gravel Springs , wells and boreholes (72) SEC 25-362
NO3 0.21-94.3
FC 0-2311 		One-off survey High levels of FS indicative of contamination from PL, related to age and density of settlement Takem et al. (2010)[25]
2Kinshasa, DR Congo Alluvial and sedimentary sequences Wells including sanitary survey Dry season
TDS 180-450
NO3 76-118
PO4 0.53-4.6
TH 110-149
Pb 0.04-0.09
Cd 0.13-0.20 		Wet season
TDS 200-710
NO3 97-198
PO4 3.6-14.6
TH 17-52.5 		Latrines, metal works, solid waste dumps are main sources of contamination Vala et al. (2011)[26]
2Dakar, Senegal Quaternary Wells (56) NO3 0-122 July-October 1997 Nitrate contamination from point-source seepage in urban areas Cissé Faye et al. (2004)[27]
2Mekelle, Ethiopia Mesozoic sediments Wells, springs and boreholes (100) SEC 542-5300
TDS 330-3454
NH4 0.01-2.38
NO3 0.21-336
Cl 5.76-298
F 0-1.27, PO4 0.001-0.58 		N/A Highly variable water quality indicative of a range of redox zones and sources of contamination Berhane and Walraevens (2013)[28]
2Bahir Dar, Ethiopia Weathered and fractured Alkaline Basalt Dug wells and protected pumps in inner, middle and outer zones (8) Middle and inner city
TDS 20-600
NO3 0.18-57.2
NH4 0-12
Cl 46-270
FC 93% of sites
Mean 1.5 log cfu
EC 80% sites mean
1.4 log cfu 		Outer city
TDS 20-70
NO3 0.08-8.8
NH4 0-12
Cl 0-40 		Sampling over a 5 month period 2006/2007 Groundwater contamination linked to population density and urbanisation. All dug wells and boreholes had microbiological contamination in excess of WHO/EU standards. Dug wells had significantly higher FC. Vala et al. (2011)[26]
1Addis Ababa, Ethiopia Volcanics Boreholes and springs (9) Alk 8-41
NO3 0.72-35
NO2 <0.01
COD 6.8-41
Cl 6.8-28
PO4 <0.03-0.1
Pb 4.6-25
SEC 300-1200
TC 0-34000 		Various The authors made a link between the surface water quality and groundwater quality. Major sources of contamination inferred were domestic waste, and industrial pollution from textile industry and petrol stations Abiye (2008)[29]
1Addis Ababa, Ethiopia Volcanics Springs and boreholes (10) Zn 0.87-146
Ni 0.31-0.98
Cu 0.44-1.82
Pb 4.3-56.2
Cd <0.1-0.2
Co <0.1-0.12 		2002 Geogenic sources of heavy metals is the likely sources of groundwater contamination in this setting due to high heavy metal concentrations in soils and rocks Alemayehu (2006)[30] Goshu and Akoma (2011)[31] Goshu et al. (2010)[32]
1Addis Ababa, Ethiopia Volcanics Springs and wells (63) Ni 2-152 µg/L
Pb <1
Co 0.5-165
As <3
Zn <20-2100
Cu 1.5-164
Cd 0.3-12.3
Cr 18.2-214 		Februrary-March 2004, July to September 2005 Urban area, leaching from polluted soils. Demlie and Wohnlich (2006)[33]
3Kisumu, Kenya (urban) Sedimentary Existing wells (191) TTC 0->100k mean 894
NO3 0.06-45 mean 15
Cl 0-225 mean 796
F 3-29.6 mean 6.2 		1998 and 2004 Density of PL within a 100 m radius was significantly correlated with nitrate and Cl but not FC (PC) Wright et al. (2013)[34]
2Lichinga, Mozambique and Timbuktu, Mali Quaternary/ Basement gneiss-granite complex Hand dug wells: Timbuktu(31), Lichinga (159) Timbuktu
SEC 221-2010
NO3-N 35 med
Cl 500 		Lichinga
SEC 220
med NO3 5.6
med
Cl 13.5 		Timbuktu September 2002 to May 2003 Lichinga, April 2002–August 2004 Contamination of groundwater sources from on site sanitation traced using N:Cl Cronin et al. (2007)[35]
3Lichinga, Mozambique Mudstone Lichinga (25) TTC, EF (Enterococi) Monthly for 1 year Higher risk at onset of the wet season and end of the dry season. Predominant source was from animal faeces rather than PL or septic tanks. (LR) Godfrey et al. (2006)[36]
2Kampala, Uganda Weathered Basement Wells and springs High density
NO3 mean 67
Cl mean 59
TC mean 14 		Low density
NO3 mean 22
Cl mean 21
TC mean 544 		Contrasting hydrological conditions Significantly higher contamination in high density regions compared to low density Barrett et al. (1998)[37]
3Kampala, Uganda Weathered Basement Springs (25) TtC (FC)
FS BLD-23000 		Monthly between September 1998-March 1999 Evidence of rapid recharge to springs following rainfall. Local environment hygiene and improved sanitary completion shown to be more important than on-site sanitation for spring protection (LR) Howard et al. (2003)[38]
3Kampala, Uganda Weathered Basement Monitoring wells (16) Dry season
SEC 272-345
P BDL-0.11
N BDL-5.5
NO3 24-144
Cl 31-50.5
TC 0-131
FC 0-35 		Wet Season
SEC 280-372
P BDL0.04
N BDL-263
NO3 24-692
Cl 28-192
TC 29-10000
FC 6-8300 		2003: weekly March-May and September in dry season, and June to August, wet season. High population density with pit latrines and livestock sources identified. Microbiological water quality deterioration after heavy rainfall Barrett et al. (1998)[37]
1Kampala, Uganda Weathered Basement Boreholes and wells (28) Limited inorganic and organic suit, no microbiology September and October 2011 Nitrate concentrations suggest poor sanitation and diffuse contamination. Nachiyunde, Kabunga et al. (2013)[39]
3Uganda, Kampala (urban) Weathered basement Piezometers (10) 1.5 m down gradient of pit latrines
NO3 5-90
Cl 50-1100
PO40.1-2
NH4 5-40 		March-August 2010 biweekly sampling PL found to be a significant source of nutrients (N) compared to waste dump. NH4 removal by nitrification Nyenje et al. (2013)[40]
1Lusaka, Zambia Dolomite Wells and streams in intensely urbanised area (9) SEC 200-710
NO3 <0.1-43
NH4 <0.25-3.5, Cl 4.6-36
PO4 <0.1-4, B <1-10, As <0.2-0.49
Pb 0.14-0.67, Hg <0.4-13 		July 2001 Values for nitrate and Hg were in excess of WHO standards on some occasions. Poor sanitation and solid waste disposal implicated. Cidu et al. (2003)[41]
2Lusaka, Zambia Dolomite Boreholes (7) FC 0-45
TC 0-58
SEC 401-1060 		Single survey Evidence for contamination in health centre boreholes by FC, poor waste management implicated Nkhuwa (2003)[42]
3Lusaka,Zambia Dolomite Private and public boreholes (N/A) Alk 124-564, NO3 0.03-39,
NO2 0.002-42, NH4 0.08-60
Cl 42-102, TC 1-TNTC
FC 21-TNTC, BOD 2-69
COD 9-320 		Various: 1995-2000 Hydrochem, microbiology and incidence of cholera outbreaks compiled to show the rapid deterioration of GW sources associated with poor sanitation Nkhuwa (2003)[42]
2Ndola, Zambia Dolomite and basement lithologies Wells (123) and boreholes (60) surface waters (41) Wells (median)
TC 7
Zn 11.4 		Boreholes (med)
TC 0
Zn 139 		April–June 2013 Geological control on trace metal contamination. TC for wells>boreholes but no FC data collected. Liddle et al (2015)[43]
3Kabwe, Zambia Dolomite and basement Private (13) and public (12) boreholes, private wells (57) Dry season
Wells
NO3 0.1-187
(18)
FC 10-6800
(180)
Boreholes NO3 0.1-38 (6)
FC <2-28 (<2) 		Wet season
Wells
NO3 0.15-174(22)
FC 2-27600
(570)
Boreholes NO3 0.1-41 (6)
FC <2-760 (<2) 		Dry and wet season 2013–2014 Widespread NO3 and FC contamination in shallow wells in both wet and dry seasons, wet>>dry. Generally good quality in peri-urban boreholes but evidence of contamination in some urban boreholes Lapworth et al (2015)[1]
3South Lunzu, Blantyre, Malawi Weathered basement Borehole, springs and dug well (9) Dry season
SEC 210-330
Cl 21-35
Fe 0.1-0.8
FC 0-5200
FS 0-640 		Wet season
SEC 306-383
Cl 14-29
Fe 0.4-0.7
FC 0-11,000
FS 0-7000 		Wet and dry season on two occasions Groundwaters highly contaminated due to poor sanitation and domestic waste disposal. 58% of residence use traditional PL Palamuleni (2002)[44]
3Southern Malawi Weathered basement Shallow wells (26) Dry season
NO3 0-2.6
NH4 detectable
most samples FC 0-9k
TC 0-17k
As, F also 		Wet season
NO3 0-4.4
TC 0-77k
FC 0-9k 		Wet and dry season Overall contamination levels higher during wet season for two districts and lower for one district and significantly higher in unprotected sources. Pritchard et al. (2008)[45]
2Tamatave and Foulpointe, Madagascar Weathered basement and unconsolidate d sediments Boreholes (53) FC 73%>0, 55% 0-10, 54%>10
NO3 4.4-35, mean 23
Pb 1-215, mean ca. 5 		One-off survey Widespread drinking water contaminated with FC and concerns over Pb from pump materials MacCarthy et al. (2013)[46]
3Epworth and Harare, Zimbabwe Granite Wells andboreholes, transect of formal and informal zones (18) NO3 0-30, mean 11
PO4 0-27.2, mean 3.03
FC 0-2, mean 0.75 (cfu x104) 		Survey carried out withduplicate sampling Pit latrines, faecal coliforms in older and informal trading areas, urban agriculture, home industries and commercial areas Zingoni et al. (2005)[47]

SEC-specific electrical conductivity, PCA=Principal component analysis, LR= logstic regression, TDS= total dissolved solids, TH=total hardness, , BOD-biological oxygen demand, COD=chemical oxygen demand, FC=faecal coliforms, EC= E. Coli, TC=total coliforms, FS=faecal streptococcus. Microbiological units as cfc/100 mL unless stated otherwise, TNCT=too numerous to count, BDL=below detection limit. Notation: 1Case-studies presenting data from a limited number of sites (n<20), limited temporal resolution as a single survey or use only basic chemical indicators and limited analysis of the results; 2 Case studies which either draw from larger data sets or include both chemical and microbiological indicators but have limited data analysis regarding sanitary risk factors; 3 Case studies with greater temporal resolution or are accompanied by a more thorough analysis of the data, for example using statistical techniques to understand the significance different risk factors on water quality observations.


Table A2 Conceptual framework for hazard sources and pathways for groundwater and surface waters.
Surface water Traditional wells a Springs Improved wells Boreholes b
Major hazard sources Surface sources: These include open defecation by humans and animals, surface soil amendments, sewers, shallow drains and surface application of waste water Surface sources: Same as for surface waters, materials used to draw water from collector contaminated with soil microbes and sanitary sources from hands

Subsurface sources: These include all buried sources of solid and liquid waste (e.g. pit latrine, soak away, waste dump, and cemetery).

Surface sources: Same as for surface waters, materials used to draw water from collector contaminated with soil microbes and sanitary sources from hands

Subsurface sources: These include all buried sources of solid and liquid waste.

Surface sources: materials used to draw water from collector contaminated with soil microbes and sanitary sources from hands

Subsurface sources: These include all buried sources of solid and liquid waste.

Subsurface hazards: These include buried sources of solid and liquid waste (e.g. pit latrine, soak away, waste dump, and cemetery).
Major hazard pathways Surface runoff, open sewer systems Surface runoff directly into well, bypass pathway from use of contaminated materials (e.g. rope or bucket). Vertical and horizontal soil flow from buried hazard sources. Surface runoff directly into spring collector, bypass pathway from use of contaminated materials (e.g. bucket). Vertical and horizontal soil flow from buried shallow hazard sources. Vertical and horizontal soil and groundwater flow to well. Crack in sanitary seal, well lining. Bypass pathway from use of contaminated materials to draw water. Horizontal groundwater flow in saturated zone to borehole intake.
Hazard susceptibility under high groundwater table conditions High at all times Very high due to lack of barrier to horizontal soil and shallow groundwater flow to well. High due to limited soil attenuation and potential activation of shallow rapid horizontal pathways to spring Moderate due to some protection from shallow horizontal soil and groundwater flow by casing. Some attenuation in saturated zone Low due to narrow diameter of casing and generally deeper casing, and high attenuation capacity in saturated zone
Hazard susceptibility to extreme rainfall conditions High due to strong link to runoff sources of contamination and limited attenuation potential Very high due to strong link to runoff sources of contamination. High due to strong link to surface runoff sources of contamination, difficulty in protecting spring catchment from encroachment by animals Moderate due to reduced lateral pathways in soil and shallow groundwater. Erosion or bypass of sanitary/annular seal possible, large diameter means this is more likely Low due to limited rapid pathways from surface or buried sources of hazards
Possible interventions for safer supply Not suitable for drinking without treatment at household level*. May be best to stop using unless there is no alternative source of water. Install well casing, sanitary seal, cover and use of alternative water lifting device such as hand pump. Generally not suitable for drinking without household treatment*. Improved citing of springs and ensure better spring protection in surface capture zone, very difficult to manage in rural areas, this is not realistic in urban/peri-urban areas. Generally not suitable for drinking without treatment*. Improved citing of wells in relation to sources of hazards. Stop main pathway from surface through use of rope and bucket, e.g. cap and install hand-pump. Deepen casing and improve sanitary seals. Often not suitable for drinking without treatment*. Improved citing of borehole in relation to sources of hazards. Maintenance: replace cracked casing, ensure adequate sanitary seals are maintained. Often suitable for drinking without treatment if well maintained/cited.

a Hand dug wells with no surface protection, b Assuming that the initial installation of a borehole is of a high standard, *Regular household treatment is not realistic in Sierra Leone or many other countries in SSA, if there is high turbidity (likely for surface waters) this may render treatment using chlorination only partially effective.

References

  1. ↑ 1.0 1.1 LAPWORTH, D J, STUART, M E, PEDLEY, S, NKHUWA DCW AND TIJANI, M N. 2015a. A review of urban and peri-urban groundwater quality studies in sub-Saharan Africa. British Geological Survey Draft Open Report OR/15/011. 133pp. (unpublished)
  2. ↑ IBEMENUGA, K N, and AVOAJA, D A. 2014. Assessment of groundwater quality in wells within the Bombali district, Sierra Leone. Animal Research International, 11, 1, 1905–1916.
  3. ↑ WRIGHT, R C. 1986. The seasonality of bacterial quality of water in a tropical developing country (Sierra Leone). Journal of Hygiene, 96, 01, 75–82.
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  31. ↑ GOSHU, G, and AKOMA, O C. 2011. Water quality assessment of underground and surface water resources of Bahir Dar and Periurban areas, north-west Ethiopia. Global Journal of Environmental Sciences, Vol. 10, 11–21.
  32. ↑ GOSHU, G, FARNLEITNER, A, MANAFI, M, and BYAMUKAMA, D. 2010. The bacteriological quality of traditional hand dug wells and protected hand pumps in Bahirdar Town and peri-urban areas, Northern Ethiopia. Proceedings of the First National Research Symposium on: Sustainable Development: A great concern in Africa, Debre Markos, Ethiopia, 247–259.
  33. ↑ DEMLIE, M, and WOHNLICH, S. 2006. Soil and groundwater pollution of an urban catchment by trace metals: case study of the Addis Ababa region, central Ethiopia. Environmental Geology, Vol. 51, 421–431.
  34. ↑ WRIGHT, J A, CRONIN, A, OKOTTO-OKOTTO, J, YANG, H, PEDLEY, S, and GUNDRY, S W. 2013. A spatial analysis of pit latrine density and groundwater source contamination. Environmental Monitoring and Assessment, Vol. 185, 12.
  35. ↑ CRONIN, A A, PEDLAY, S, HOADLY, A W, KOUONTO KOMOU, F, HALDIN, L, GIBSON, J, and BRESLIN, N. 2007. Urbanisation effects on groundwater chemical quality: findings focusing on the nitrate problem from 2 African cities reliant on on-site sanitation. Journal of Water and Health, Vol. 5, 441–454.
  36. ↑ GODFREY, S, TIMO, F, and SMITH, M. 2006. Microbiological risk assessment and management of shallow groundwater sources in Lichinga, Mozambique. Water and Environment Journal, Vol. 20, 194–202.
  37. ↑ 37.0 37.1 BARRETT, M H, HOWARD, A G, PEDLEY, S, TAYLOR, R G, and NALUBEGA, M. 1998. A comparison of the extent and impacts of sewage contamination on urban groundwater in developed and developing countries. WHO conference: Water, Sanitation and Health, 24–28 November, Bad Elster, Germany.
  38. ↑ HOWARD, G, PEDLEY, S, BARRETT, M, NALUBEGA, M, and JOHAL, K. 2003. Risk factors contributing to microbiological contamination of shallow groundwater in Kampala, Uganda. Water Research, Vol. 37, 3421–3429.
  39. ↑ NACHIYUNDE, K, IKEDA, H, OKUDA, T, and NISHIJIMA, W. 2013. Assessment of dissolved heavy metal pollution in five provinces of Zambia. Journal of Environmental Protection, Vol. 4, 80–85.
  40. ↑ NYENJE, PM, FOPPEN, JW, KULABAKO, R, MUWANGA, A, AND UHLENBROOK, S. 2013. Nutrient pollution in shallow aquifers underlying pit latrines and domestic solid waste dumps in urban slums. Journal of environmental management, 122, 15–24.
  41. ↑ CIDU, R, DE WAELE, J, DI GREGARIO, F, and FOLLESA, R. 2003. Geochemistry of groundwater in an intensely urbanised karst area (Lusaka, Zambia) GeoActa, Vol. 2, 35–42.
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  43. ↑ LIDDLE, E S, MAGER, S M, and NEL, E L. 2014. The importance of community-based informal water supply systems in the developing world and the need for formal sector support. The Geographical Journal.
  44. ↑ PALAMULENI, L G. 2002. Effect of sanitation facilities, domestic solid waste disposal and hygiene practices on water quality in Malawi’s urban poor areas: a case study of South Lunzu Township in the city of Blantyre. Physics and Chemistry of the Earth, Parts A/B/C, Vol. 27, 845–850.
  45. ↑ PRITCHARD, M, MKANDAWIRE, T, and O’NEILL, J G. 2008. Assessment of groundwater quality in shallow wells within the southern districts of Malawi. Physics and Chemistry of the Earth, Parts A/B/C, Vol. 33, 812–823.
  46. ↑ MACCARTHY, M F, ANNIS, J E, and MIHELCIC, J R. 2013. Unsubsidised Self-Supply in Eastern Madagascar. Water Alternatives, Vol. 6, 424–438. MALOMO, S, OKUFARASIN, V A, OLORUNNIWO, M A, and OMODE, A A. 1990. Groundwater Chemistry of Weathered Zone Aquifers of an Area Underlain by Basement-Complex Rocks. Journal of African Earth Sciences, Vol. 11, 357–371.
  47. ↑ ZINGONI, E, LOVE, D, MAGADZA, C, MOYCE, W, and MUSIWA, K. 2005. Effects of a semi-formal urban settlement on groundwater quality: Epworth (Zimbabwe): Case study and groundwater quality zoning. Physics and Chemistry of the Earth, Parts A/B/C, Vol. 30, 680–688.
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