Details

Autor(en) / Beteiligte

• Ravenscroft, P.
• Mahmud, Z.H.
• Islam, M. Shafiqul
• Hossain, A.K.M.Z.
• Zahid, A.
• Saha, G.C.
• Zulfiquar Ali, A.H.M.
• Islam, Khairul
• Cairncross, S.
• Clemens, J.D.
• Islam, M. Sirajul

Titel

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

Ist Teil von

• Water research (Oxford), 2017-11, Vol.124, p.192-201

Ort / Verlag

England: Elsevier Ltd

Erscheinungsjahr

2017

Quelle

Elsevier ScienceDirect Journals

Beschreibungen/Notizen

• 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 3.3–23.3% 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. [Display omitted] •Severe faecal pollution of groundwater from latrines is limited to a near-field.•In the far-field, faecal pollution is low-level, discontinuous and impersistent.•Latrine pollution of groundwater is a minor contributor to diarrhoeal disease.•Expanding latrine coverage will have little impact on groundwater used for drinking.