Concern for saline and microbial quality post-December 2004 tsunami, led to a field based surveillance study to systematically investigate the sanitary hazards which cause faecal contamination of groundwater. In seven islands, two duplicate sample sets, in two surveys, revealed that only 6.4% of the 173 well water samples (combining both surveys) satisfied the WHO Drinking Water Quality Guideline for 44˚C thermo-tolerant (Faecal) Coliform (FC) indicator value (zero cfu/100ml sample). Based on a combined risk analysis of Sanitary Hazard Score (SHS) and FC counts, more than 57.7% of the study wells were classified as at very high (FC: 100 to >1000 cfu/100ml; and SHS: ≥9) microbial health risk. During this study, fundamental changes were made to the published generic sanitary inspection method (WHO, 1997) for identifying sanitary hazards, for its application in the extremely vulnerable hydro-geological setting of the Maldives. However, the most important hazard controlling the intensity of faecal contamination in the Maldives is the safe separation distance between a latrine seepage point and the well. It was demonstrated that, due to the prevailing hydro-geological conditions and the well and sanitation system densities, safe separation distance cannot be achieved. Consequently, septic tank effluent quality must be greatly improved.
As practised in the remote Maldives islands, groundwater exploitation using open dug wells with on-site sanitation systems causes major microbial contamination of well water. Surveys show that 75% of the Maldives population currently rely on rainwater tanks for drinking water. Global climatic change causes prolonged drought periods and extensive rainfall events causing flooding. In addition to rainwater storage tanks, the very limited land area makes the utilisation of the natural underground reservoir an essential water source for the remote Maldives islands. Therefore, it becomes vital to protect the groundwater quality in these islands.Using methods published by World Health Organisation (WHO) for combined hazard identification and faecal contamination, a surveillance study of open dug wells was carried out in six selected islands of the Maldives. The aims were to assess the current risks and sustainability of the open dug wells in the study areas with respect to sanitation related health issues. The field study involved systematically collecting data about sanitary hazards in the neighbourhood of wells and well water quality, including thermo-tolerant faecal coliform counts. The results showed that the great majority (83%) of wells were, as expected, faecally contaminated. However, the expected benefit of using combined sanitary survey and faecal contamination level assessment to prioritize specific remedial actions to improve the microbial quality of well water was not realized in this study, in contrast to earlier published studies. The principal reasons for this methodological failure are: Irrespective of the impact of climate change on sea level and rainfall patterns, it is concluded that current on-site sanitation practices are unsustainable. A major programme of disciplined construction of septic tanks with careful attention to tile field design would be required to address the problem of faecal contamination of the aquifer. the geological setting of the Maldives is extremely vulnerable overall, particularly since there is effectively no soil layer
A well surveillance study carried out in nine Divisional Secretariat Divisions on the west coast of Sri Lanka showed that 70.3% of 101 well sampling points were microbially contaminated with equal to, or greater than, faecal coliform grade C (11 - 100 cfu/100 mL). Due to the very vulnerable hydro-geological setting of the coastal sand, laterite and alluvium aquifers occurring in the study areas, the recommended safe separation distance between an on-site sanitation system and a well could not be achieved. Hence, a cardinal rule of well protection was observed to be broken at almost every well study site. The existing excreta disposal systems need to be improved or replaced with more efficient ones before the impact of other sanitary hazards at the well, and wellhead area, on the microbial quality of well water, can be determined and addressed. The published (WHO, 1997) sanitary survey forms for open dug wells and tube wells need to be modified in the context of the study areas described. Based on a comparison of three different statistical methods used to assess the relative significance of each sanitary hazard modification to the methodology for determining the sanitary hazard index (SHI) was prescribed
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