Assessment of the water sources for potential channels of faecal contamination within Vhembe District Municipality using sanitary inspections and hydrogen sulphide test.

Numerous human activities and poor sanitation management cause public health concern, particularly in rural communities without reliable water supply systems and resources for the monitoring of the quality of their water sources. This study assessed the relationship between observed sanitary risks and hydrogen sulphide (H2S) strip test results in the identification of faecal contamination of various water sources used at household level in rural areas of the Vhembe District Municipality. The highest percentage sanitary risk scores ranging from 50 to 100% were recorded for both river and dam water commonly used by the households for multiple purposes, including drinking. All the surface water samples (100%) also tested positive for H2S production, which is linked to the contamination of water sources by bacteria of faecal origin. The overall results showed a significant and positive correlation (r = 0.623, p = 0.003 in the wet season and r = 0.504, p = 0.017 in the dry season) between sanitary risk scores and H2S strip test results. In low resource settings, the use of sanitary inspections combined with the inexpensive and easy-to-use H2S strip tests can be effective as drinking water quality management tools to raise an awareness among community members of the faecal contamination of their water sources.

Evaluation of the efficiency of selected wastewater treatment processes in removing selected perfluoroalkyl substances (PFASs).

In this study, the efficiencies of selected wastewater treatment plants (WWTPs) to remove selected perfluoroalkyl substances (PFASs) during wastewater treatment processes were evaluated. For this purpose, influent samples from Daspoort, Zeekoegat and Phola WWTPs, were initially screened for the presence of sixteen different PFASs of which only seven were detected. These include: perfluorobutanoic acid (PFBA), perfluoro-n-pentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), perfluorodecanoic acid (PFDA), perfluorohexane sulfonate (L-PFHxS), and perfluorooctane sulfonate (L-PFOS). To determine the concentrations of these PFASs, wastewater samples were subjected to solid-phase extraction followed by liquid chromatography-tandem mass spectrometry. The results showed that L-PFOS was the dominant compound with the highest concentration of 508 ± 258 ng/L at Daspoort WWTP. Overall, the three WWTPs could not achieve the complete influent-to-effluent removal of the PFASs and the best removals were observed at Zeekoegat WWTP. The removal efficiency of the different unit processes varied from one plant to another and also from each type of PFASs. At Daspoort, the removal efficiency of the primary settling tanks was poor and the highest removal reached 39% for PFHxA. The activated sludge (AS) of this WWTP achieved the highest removal of 84% for the L-PFOS. At Zeekoegat, the AS achieved the highest removal of 94% for the L-PFOS. The anaerobic pond at Phola achieved a higher removal of 80% for the L-PFOS. However, no removal was observed downstream of the biological filter for the same compound. Poor removal efficiency was reported downstream of the wetland at Phola except for the PFOA (16%).

The Impact of Social Disparities on Microbiological Quality of Drinking Water Supply in Ugu District Municipality of Kwazulu-Natal Province, South Africa.

This study was undertaken to highlight the social disparity between rural and urban areas in terms of housing patterns, provision of safe drinking water, access to sanitation facilities, education, employment rate and health-related to diarrhoeal episodes in Ugu District Municipality of KwaZulu-Natal Province of South Africa. To achieve this aim, a survey was conducted using a structured questionnaire. Drinking water samples were collected from the point of supply and the storage containers to assess the microbiological quality of drinking water in both rural and urban areas. Results of this study revealed prominent residential segregation between rural and urban communities, whereby the houses in the rural areas were generally constructed with corrugated iron sheets, or mud brick and mortar whereas conventional brick-and-mortar construction was used to build those in the urban areas. All of the urban households had flush toilets in their houses (100%), while 98.2% of the rural households were relying on pit latrines and 1.8% were reported to defecate in an open field. The District unemployment rate was at 58.1% in rural areas and none among the urban community. Results also showed that only 13.6% of the rural dwellers completed their secondary education compared to 70.4% of the urban areas. The diarrhoeal episodes were high in rural areas (34.1%) while none of these episodes was reported in urban areas. Great disparity in the water supply persists between rural and urban communities. For the former, the standpipes located outside their homes (90.9%) remain the sole mode of access to drinking water, while in the urban area, all households had pipes/taps inside their houses. Assessment of the drinking water quality revealed only the stored drinking water used by the rural community of Ugu District was contaminated. High prevalence of E. coli ranging from 63.3 % to 66.7% was recorded only in stored water after the sequencing of 16S rRNA genes. Species-specific PCR primers exposed the presence of enteropathogenic Escherichia coli at a rate ranging between 1.4% and 3.7% in this water Overall, this study has been able to highlight the disparity left by the legacy of racial segregation in the Ugu Municipality District. Therefore, the local government must intervene in educating homeowners on safe water storage practices.

Kinetics of petroleum oil biodegradation by a consortium of three protozoan isolates (Aspidisca sp., Trachelophyllum sp. and Peranema sp.).

Petroleum oil is a complex mixture of substances, the majority of which are hydrocarbons; the latter represent an extremely important and heterogeneous group of compounds that find their way into water resources by anthropogenic or natural ways. The majority of toxic hydrocarbon components of petroleum are biodegradable, where bioremediation using microbial species has become an integral process for the restoration of oil-polluted areas. In this study, three bioremediation processes, namely natural attenuation, nutrient supplementation by adding glucose and biostimulation by adding Tween® 80, were carried out in various petroleum hydrocarbon concentrations in polluted water media using a consortium of three protozoan isolates (Aspidisca sp., Trachelophyllum sp. and Peranema sp.). A first-order kinetics model was fitted to the biodegradation data to evaluate the biodegradation rate and to determine the corresponding half-life time. First-order kinetics satisfactorily described the biodegradation of the petroleum-based contaminants under abiotic conditions. The results showed an increase in the percentage removal of petroleum oil at the lower petroleum concentrations and a gradual percentage decrease in removing petroleum oil residues occurred when there was an increase in the initial concentrations of the petroleum oil: 39%, 27%, 22%, 12%, 10% for various petroleum oil concentrations of 50, 100, 150, 200, 250 mg/L, respectively. A similar trend was also observed in the glucose-supplemented culture media where the reduction was 45% and 78% for petroleum concentrations of 250 mg/L and 50 mg/L, respectively. Biodegradation of between 33 and 90% was achieved at a Tween® 80 concentration of between 50 mg/L and 250 mg/L. The degradation rate constants for the natural attenuation process ranged between ≥0 to ≤0.50, ≥0 to ≤0.35, ≥0 to ≤0.25, ≥0 to ≤ 0.14 and ≥ 0 to ≤0.11 for petroleum oil concentrations varying from 50, 100, 150, 200 and 250 mg/L, respectively, during the study after 30 days. In the presence of glucose as a nutrient supplement, the degradation rate constants increased from 0 day-1 to 0.8 day-1 when exposed to the lowest oil concentration of 50 mg/L, while the lowest rate constants (from 0 day-1 to 0.25 day-1) were observed at the highest petroleum oil concentration of 250 mg/L for the same period. Overall enhancement of the degradation rates was achieved when adding the Tween® 80 surfactant compared to the first two biodegradation processes. The longest half-life was achieved after 217 days during the natural attenuation process for samples with an oil concentration of 250 mg/L and this was reduced to 85 days using the glucose-supplemented process. There was a further decrease to 45 days when Tween® 80 surfactant was added during the biostimulation process. The highest efficiency of ≥20% of Tween® 80 was observed between 6 and 18 days and thereafter it decreased slightly to ≤20%.

The impact of zinc oxide nanoparticles on the bacterial microbiome of activated sludge systems.

The expected growth in nanomaterial applications could result in increased amounts of nanoparticles entering municipal sewer systems, eventually ending up in wastewater treatment plants and therefore negatively affecting microbial populations and biological nutrient removal. The aim of this study was to ascertain the impact of zinc oxide nanoparticles (nZnO) on the bacterial microbiome of an activated sludge system. A metagenomic approach combined with the latest generation Illumina MiSeq platform and RDP pipeline tools were used to identify and classify the bacterial microbiome of the sludge. Results revealed a drastic decrease in the number of operational taxonomic units (OTUs) from 27 737 recovered in the nZnO-free sample to 23 743, 17 733, and 13 324 OTUs in wastewater samples exposed to various concentrations of nZnO (5, 10 and 100 mg/L nZnO, respectively). These represented 12 phyla, 21 classes, 30 orders, 54 families and 51 genera, completely identified at each taxonomic level in the control samples; 7-15-25-28-20 for wastewater samples exposed to 5 mg/L nZnO; 9-15-24-31-23 for those exposed to 10 mg/L and 7-11-19-26-17 for those exposed 100 mg/L nZnO. A large number of sequences could not be assigned to specific taxa, suggesting a possibility of novel species to be discovered.

Seasonal variation of nutrient loads in treated wastewater effluents and receiving water bodies in Sedibeng and Soshanguve, South Africa.

The discharge of inadequately treated wastewater effluent presents a major threat to the aquatic environment and public health worldwide. As a water-scarce country, South Africa is facing an alarming situation since most of its wastewater discharges are not meeting the permissible limit. The aim of this study was to assess the physicochemical quality of treated wastewater effluents and their impact on receiving water bodies. During the study period, pH, temperature, free chlorine residue (Cl(-)), dissolved oxygen (DO), nitrate (NO3 (-1)), orthophosphate (PO4 (-3)) and chemical oxygen demand (COD) were measured in order to ascertain whether the selected wastewater systems in Sedibeng and Soshanguve complied with the South African and World Health Organization standards during wet and dry seasons. These parameters were analysed for samples collected from raw wastewater influent, treated wastewater effluent and receiving water bodies. The study was carried out between August 2011 and May 2012, and samples were collected on a weekly basis during both seasons. The physicochemical quality of effluents did not comply with the regulatory limits set by South Africa in terms of pH in Meyerton, Rietgat and Sandspruit (pH 7.6 to 8.1); free chlorine in Sandspruit (0.27 ± 0.05 mg/L); nitrate in Leeuwkuil and Rietgat (2.1 and 3.8 mg/L, respectively) during the wet season; orthophosphate in Meyerton during the wet season and in Sandspruit during the dry season (1.3 mg PO4 (-3) as P/L and 1.1 mg PO4 (-3) as P/L, respectively); and chemical oxygen demand in Rietgat during the dry season and in Sandspruit during the wet season (75.5 and 35 mg/L, respectively). Furthermore, the quality of the receiving water bodies did not comply with the South African standards recommended for pH, chemical oxygen demand and orthophosphate and DO (5 mg/L) in Rietgat during the wet season. The geometric mean of the water quality index values ranged between 32.4 and 36.9 for the effluent samples and between 38.1 and 65.7 for the receiving water bodies. These findings revealed that the receiving water bodies were classified as having "poor" quality status, except Leeuwkuil receiving water body (Vaal River) and Sandspruit upstream (Sandspruit stream). The dry season showed a relatively lower water quality index. This situation might be attributed to the higher amount of organic matter and lower microbial activities in the receiving water bodies. This study suggests that wastewater effluents and receiving water systems should be monitored regularly to ensure best practices with regard to nutrient treatment and discharge of wastewater.

Population Growth and Its Impact on the Design Capacity and Performance of the Wastewater Treatment Plants in Sedibeng and Soshanguve, South Africa.

This study investigated the effects of population growth on the performance of the targeted wastewater treatment plants in Sedibeng District and Soshanguve peri-urban area, South Africa. The impact of population growth was assessed in terms of plant design, operational capacity (flow rate) and other treatment process constraints. Between 2001 and 2007, the number of households connected to the public sewerage service increased by 15.5, 17.2 and 37.8% in Emfuleni, Lesedi and Midvaal Local Municipalities, respectively. Soshanguve revealed a 50% increment in the number of households connected to the sewerage system between 1996 and 2001. Except for Sandspruit (-393.8%), the rate of influent flows received by Meyerton increased by 6.8 ML/day (67.8%) and 4.7 ML/day (46.8%) during the dry and wet seasons, respectively. The flow rate appeared to increase during the wet season by 6.8 ML/day (19.1%) in Leeuwkuil and during the dry season by 0.8 ML/day (3.9%) in Rietgat. Underperformance of the existing wastewater treatment plants suggests that the rapid population growth in urban and peri-urban areas (hydraulic overloading of the wastewater treatment plants) and operational constraints (overflow rate, retention time, oxygen supply capacity of the plants and chlorine contact time) resulted in the production of poor quality effluents in both selected areas. This investigation showed that the inefficiency of Meyerton Wastewater Treatment Plant was attributed to the population growth (higher volumes of wastewater generated) and operational constraints, while the cause of underperformance in the other three treatment plants was clearly technical (operational).

Prevalence of enteropathogenic bacteria in treated effluents and receiving water bodies and their potential health risks.

The failure of wastewater treatment plants to produce effluents of a high microbiological quality is a matter of great concern in terms of water resource pollution. A more serious concern is that this water source is used by communities in developing countries for multiple purposes, which include drinking, recreation and agriculture. The current study investigated the prevalence and potential health risks of enteropathogenic bacteria (Salmonella typhimurium, Shigella dysenteriae and Vibrio cholerae) in the treated effluents of three selected South African Wastewater Treatment Works as well as their receiving water bodies. Culture-based and polymerase chain reaction techniques were used to detect and identify the pathogenic bacteria. The conventional methods revealed that of the 272 water samples collected, 236 samples (86.8%) tested presumptively positive for Salmonella spp., 220 samples (80.9%) for Shigella spp. and 253 samples (93.0%) for V. cholerae. Molecular test results indicated that out of the randomly selected presumptive positive samples (145), zero to 60% of samples were positive for S. typhimurium and S. dysenteriae and 20% to 60% for V. cholerae. For the health risk assessment, the daily combined risk of S. typhimurium, S. dysenteriae and V. cholerae infection was above the lowest acceptable risk limit of 10(-4) as estimated by the World Health Organization for drinking water. This study showed that the target treated wastewater effluents and their receiving water bodies could pose a potential health risk to the surrounding communities.

Diversity and antibiograms of bacterial organisms isolated from samples of household drinking-water consumed by HIV-positive individuals in rural settings, South Africa.

Diarrhoea is a hallmark of HIV infections in developing countries, and many diarrhoea-causing agents are often transmitted through water. The objective of the study was to determine the diversity and antibiotic susceptibility profiles of bacterial organisms isolated from samples of household drinking-water consumed by HIV-infected and AIDS patients. In the present study, household water stored for use by HIV-positive patients was tested for microbial quality, and isolated bacterial organisms were analyzed for their susceptibility profiles against 25 different antibiotics. The microbial quality of water was generally poor, and about 58% of water samples (n=270) were contaminated with faecal coliforms, with counts varying from 2 colony-forming unit (CFU)/100 mL to 2.4x104 CFU/100 mL. Values of total coliform counts ranged from 17 CFU/100 mL to 7.9x105/100 mL. In total, 37 different bacterial species were isolated, and the major isolates included Acinetobacter lwoffii (7.5%), Enterobacter cloacae (7.5%), Shigella spp. (14.2%), Yersinia enterocolitica (6.7%), and Pseudomonas spp. (16.3%). No Vibrio cholerae could be isolated; however, V. fluvialis was isolated from three water samples. The isolated organisms were highly resistant to cefazolin (83.5%), cefoxitin (69.2%), ampicillin (66.4%), and cefuroxime (66.2%). Intermediate resistance was observed against gentamicin (10.6%), cefepime (13.4%), ceftriaxone (27.6%), and cefotaxime (29.9%). Levofloxacin (0.7%), ceftazidime (2.2%), meropenem (3%), and ciprofloxacin (3.7%) were the most active antibiotics against all the microorganisms, with all recording less than 5% resistance. Multiple drug resistance was very common, and 78% of the organisms were resistant to three or more antibiotics. Education on treatment of household water is advised for HIV-positive patients, and measures should be taken to improve point-of-use water treatment as immunosuppressed individuals would be more susceptible to opportunistic infections.

Comparing the tolerance limits of selected bacterial and protozoan species to nickel in wastewater systems.

Heavy-metal resistant microorganisms play a significant role in the treatment of industrial wastewater. The detoxifying ability of these resistant microorganisms can be manipulated for bioremediation of heavy metals in wastewater systems. This study aimed at comparing the tolerance limit of selected wastewater protozoan species (Aspidisca sp., Trachelophyllum sp. and Peranema sp.) against Ni(2+) with that of selected bacterial species (Bacillus licheniformis-ATCC12759, Brevibacillus laterosporus-ATCC64 and Pseudomonas putida-ATCC31483) commonly found in wastewater systems. The isolates were exposed to various concentrations of Ni(2+) in mixed liquor and their tolerance to Ni(2+) assessed at different temperatures (25°C, 30°C, 35°C and 40°C) and pHs (4, 6, 7, 8 and 10). The physicochemical parameters such as chemical oxygen demand (COD) and dissolved oxygen (DO) of the media and the growth rates of the isolates were measured using standard methods. In terms of their minimum inhibitory concentrations (MIC), the results revealed that the isolates could tolerate Ni(2+) at concentrations ranging between 32 and 52ppm for protozoa and between 52 and 84ppm for bacteria. B. licheniformis-ATCC12759 was the most tolerant bacterial species (MIC: 84ppm-Ni(2+)) while Peranema sp. was the most tolerant protozoan species (MIC: 52ppm-Ni(2+)). At 10 and/or 20ppm-Ni(2+) the growth of B. licheniformis-ATCC12759 (6.30 days(-1) for 10 and 5.73 days(-1) for 20ppm-Ni(2+)), P. putida-ATCC31483 (6.02 days(-1) for 10 and 5.31 days(-1) for 20ppm-Ni(2+)) and Peranema sp. (2.15 days(-1) for 10ppm-Ni(2+)) was stimulated after one day of incubation. Statistical evidence showed significant differences (p=0.0065) between the MIC of the six isolates and positive correlations between COD and the growth rates of isolates (r=0.8999/0.8810 for bacteria/protozoa). The tolerance limit of all isolates was significantly dependent on the pH and the temperature. The study suggests that these isolates can be used for the bioremediation of nickel in industrial wastewater systems.

Prevalence of Escherichia coli O157:H7 among diarrhoeic HIV/AIDS patients in the Eastern Cape Province-South Africa.

This study investigated the prevalence of Escherichia coli O157:H7 in the stool of confirmed and non-confirmed diarrhoeic HIV/AIDS patients. Escherichia coli O157:H7 was isolated by culture-based and immunomagnetic separation from three hundred and sixty stool swabs. Identification was by conventional IMViC, 20E API and molecular techniques. Confirmed and non-confirmed diarrhoeic HIV/AIDS patients had 56.5% (74/131) and 43.5% (57/131) respectively of E. coli O157:H7. Molecular results indicated that the prevalence of E. coli O157:H7 was 12.16% (9/74) and 8.77% (5/57) from stool swabs of confirmed and non-confirmed diarrhoeic HIV/AIDS patients. Antimicrobial resistance was higher for E. coli O157:H7 isolates from stools of confirmed HIV/AIDS than it was for non-confirmed HIV/AIDS patients. Escherichia coli O157:H7 might be a silent cause of diarrhoea in HIV/AIDS patients. It is recommended that HIV/AIDS patients with diarrhoea should be screened for E. coli O157:H7 and surveillance programmes for these bacteria should be established in both urban and rural areas of South Africa.

Prevalence and antimicrobial susceptibility of Escherichia coli O157:H7 in vegetables sold in the Amathole District, Eastern Cape Province of South Africa.

Fresh vegetables have been implicated in outbreaks of Escherichia coli O157:H7 in most parts of the world. Microbiological quality of vegetables used as recipes for salads is very crucial. Residents of the Amathole District in the Eastern Cape Province of South Africa consume salads frequently, although the microbial quality of recipe vegetables is questionable. The present study investigated the prevalence and antimicrobial susceptibility of E. coli O157:H7 isolated from selected vegetables sold within the Amathole District. One hundred eighty samples of the vegetables were analyzed. Strains of E. coli O157:H7 were isolated by enrichment culture and by immunomagnetic separation and identified by conventional and molecular techniques. In three settlements in this district, the mean counts of presumptive E. coli O157 for the vegetables ranged between 9 x 10(3) and 1.6 x 10(6) CFU/g for Fort Beaufort, 1.6 x 10(3) and 1.6 x 10(5) CFU/g for Mdantsane, and 1.3 x 10(3) and 4.1 x 10(4) CFU/g for Alice. Four (10.3%) of 39 vegetable samples were confirmed to carry E. coli O157:H7. Four representative E. coli O157:H7 isolates from these vegetables were susceptible to at least one of the eight antimicrobial agents tested against them. Even though the prevalence of E. coli O157:H7 was low and those isolated were susceptible to most of the antimicrobials, there remains a need for E. coli O157:H7 surveillance in vegetables used in salad recipes in urban and rural areas of South Africa.

Prevalence and potential link between E. coli O157:H7 isolated from drinking water, meat and vegetables and stools of diarrhoeic confirmed and non-confirmed HIV/AIDS patients in the Amathole District - South Africa.

AIM: The current study investigated the prevalence and molecular relatedness between Escherichia coli O157:H7 isolated from water, meat and meat products and vegetables and from stools of confirmed and non-confirmed Human Immune Virus/Acquired Immunodeficiency Syndrome (HIV/AIDS) patients with diarrhoea. METHODS AND RESULTS: Culture-based and polymerase chain reaction techniques were used to identify E. coli O157:H7. Thirty-five per cent of meat products, 25.5% of water, 21.7% of vegetables as well as 56.5% and 43.5% of stools of confirmed and non-confirmed HIV/AIDS patients, respectively, were presumptively positive with E. coli O157. Molecular results indicated that 10.3%, 8.6% and 7.8% of the vegetables, water and meat products examined carried E. coli O157:H7, which had homologous fliC(H7), rfbE(O157) and eaeA genetic loci to the genes of some E. coli O157:H7 isolated from 12.2% and 8.8% of the stools of confirmed and non-confirmed HIV/AIDS patients, respectively. CONCLUSIONS: Water, meat and meat products and vegetables are potential sources of E. coli O157:H7 that are potentially capable of causing diarrhoea in humans especially HIV/AIDS patients. SIGNIFICANCE AND IMPACT OF THE STUDY: Great care should be exercised to ensure that water and foods consumed by HIV/AIDS patients are safe, as contaminated water and foods can cause secondary infections in these patients.

Phosphorus and nitrate removal by selected wastewater protozoa isolates.

In the present study, the efficiency often selected wastewater protozoa in the removal of phosphorus and nitrogen and their effects on other physico-chemical parameters was investigated. Protozoa were isolated from the aerobic zone of Daasport wastewater treatment plant, in Pretoria, South Africa, using the modified Chalkey's medium. The isolates were screened for nutrient removal ability in shake flasks, at laboratory temperatures for 96 h. During each sampling, aliquot samples were collected for the analysis of phosphorus, nitrate-nitrogen, Chemical Oxygen Demand (COD), Dissolved Oxygen (DO), pH, of the mixed liquor including the growth rate of the isolates using standard methods. The results indicated a steady increase in growth rate of the isolates and all the isolates used in this study showed some measure of phosphorus and nitrate removal ability. In the presence of the test protozoa isolates, an increase in COD and a decrease in DO were noted in the mixed liquor inoculated with the organisms, while the pH only increases slightly. This study revealed a significant correlation between growth rate and nutrient removal (R = -0.806, p < 0.001 for phosphorus; R = -0.799, p < 0.01 for nitrate). The present study has been able to show that certain protozoa isolates have the ability to biologically remove phosphorus and nitrate from effluent. Consequently, it would be necessary to identify what strains of protozoa are capable of excess phosphorus and nitrogen uptake for the treatment of wastewater.

Combining chlorination and chloramination processes for the inhibition of biofilm formation in drinking surface water system models.

AIMS: The aim of this study was to investigate the inhibition of biofilm formation on stainless steel (SS) and galvanized mild steel (MS) in chlorine (AFC(1)) and chlorine-monochloramine treated waters (AFC(2)M). METHODS AND RESULTS: Disinfection was carried out using 2.5 mg l(-1) free chlorine followed by 1.5 mg l(-1) monochloramine, with non-disinfected water used as control water. Results of the standard spread plate procedure, DAPI epifluorescence microscopy and scanning electron microscopy revealed bacterial colonization of SS and MS exposed to non-disinfected and chlorinated waters between 24 and 720 h, while no bacterial adhesion was detected on SS and MS exposed to AFC(2)M between 48 and 504 h. CONCLUSIONS: The inability of bacteria to grow on SS and MS was observed only when 0.35 mg l(-1) residual monochloramine was maintained throughout the system. SIGNIFICANCE AND IMPACT OF THE STUDY: This demonstrates the inability of chlorine alone to inhibit bacterial growth and suggests a combination of chlorine and monochloramine as a more effective treatment for drinking water, especially for rural communities with very poor source waters in Africa.