The public health significance of latrines discharging to groundwater used for drinking

WATER RESEARCH

卷:124

Article

Mahmud, Z. H.¹  Islam, M. Shafiqul¹  Hossain, A. K. M. Z.¹  Zahid, A.²  Saha, G. C.³  Ali, A. H. M. Zulfiquar⁴  Islam, Khairul⁵  Cairncross, S.⁶  Islam, M. Sirajul¹ 

[1] Int Ctr Diarrhoeal Dis Res, 68 Shaheed Tajuddin Ahmed Sarani, Dhaka 1212, Bangladesh

[2] Bangladesh Water Dev Board, Green Rd, Dhaka, Bangladesh

[3] Dhaka Univ Engn & Technol, Shimultoly Rd, Gazipur, Bangladesh

[4] Univ Dhaka, Dept Soil Water & Environm, Dhaka 1000, Bangladesh

[5] WaterAid Bangladesh, House 97-B,Rd 25,Block A, Dhaka 1213, Bangladesh

[6] London Sch Hyg & Trop Med, Dept Dis Control, Keppel St, London WC1E 7HT, England

关键词: Faecal coliforms;    Latrines;    Groundwater pollution;    Bangladesh;    Drinking water;    Risk;   

DOI  :  10.1016/j.watres.2017.07.049

来源: Elsevier

【 摘 要 】

Faecal contamination of groundwater from pit latrines is widely perceived as a major threat to the safety of drinking water for several billion people in rural and peri-urban areas worldwide. On the floodplains of the Ganges-Brahmaputra-Meghna delta in Bangladesh, we constructed latrines and monitored piezometer nests monthly for two years. We detected faecal coliforms (FC) in 3.3-233% of samples at four sites. We differentiate a near-field, characterised by high concentrations and frequent, persistent and contiguous contamination in all directions, and a far-field characterised by rare, impersistent, discontinuous low-level detections in variable directions. Far-field FC concentrations at four sites exceeded 0 and 10 cfu/100 ml in 2.4-9.6% and 0.2-2.3% of sampling events respectively. The lesser contamination of in-situ groundwater compared to water at the point-of-collection from domestic wells, which itself is less contaminated than at the point-of-consumption, demonstrates the importance of recontamination in the well-pump system. We present a conceptual model comprising four sub-pathways: the latrine aquifer interface (near-field); groundwater flowing from latrine to well (far-field); the well-pump system; and post-collection handling and storage. Applying a hypothetical dose-response model suggests that 1-2% of the diarrhoeal disease burden from drinking water is derived from the aquifer, 29% from the well-pump system, and 70% from post-collection handling. The important implications are (i) that leakage from pit latrines is a minor contributor to faecal contamination of drinking water in alluvial deltaic terrains; (ii) fears of increased groundwater pollution should not constrain expanding latrine coverage, and (iii) that more attention should be given to reducing contamination around the well-head. (C) 2017 Elsevier Ltd. All rights reserved.

【 授权许可】

Free