Sanitary Hazards and Microbial Quality of Open Dug Wells in the Maldives Islands

Abstract

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.

Estimating transient freshwater lens dynamics for atoll islands of the Maldives

“…Water resources of the Republic of the Maldives are under serious immediate and future threat due to changing rainfall patterns, sea-level rise and associated coastal degradation (Pernetta, 1992;Lal et al, 2002;Mörner et al, 2004;Woodworth, 2005;Woodroffe, 2008), an increasing urban population for many of the islands, limited rainwater harvesting capacity, and contamination due to seawater intrusion, overwash events (Woodroffe, 2008;Barthiban et al, 2012), and land surface derived pollution. The nation, located in the Indian Ocean, comprises about 200 inhabited small coral atoll islands and has a total population of approximately 320,000.…”

Applicability of a Surveillance Methodology for the Microbiological Safety of Well Water Supplies, in a Highly Vulnerable Hydrogeological Setting——A Case Study Based Findings from the West Coastal Area of Sri Lanka

“…The published [7] sanitary survey forms for open dug wells and tube wells need to be modified according to the context of the Negombo study areas. Barthiban et al [10] showed that the published [7] surveillance form needed to be modified to be applied in the context of the Maldives islands which was characterized by: -Very vulnerable hydrogeological conditions aquifer with shallow groundwater Therefore, in conclusion, the published surveillance forms need revision based on the specific hydrogeological and sanitation densities of the study area.…”

“…Nevertheless, due to the very vulnerable hydrogeological conditions, and bearing in mind the fact that it is not feasible to maintain a safe separation distance between the on-site sanitation system and the well, faecal contamination of well water from on-site sanitation system, (similar to the context of the Maldives islands [10]) can also considered to be local.…”

The Effectiveness of Sanitary Inspections as a Risk Assessment Tool for Thermotolerant Coliform Bacteria Contamination of Rural Drinking Water: A Review of Data from West Bengal, India

“…Some studies have looked at the relationship between the overall SIS and FIB concentration. [12][13][14][15] Others have analyzed the relationship between individual SI risk questions and FIB concentration using logistic regression. 12,16 Further studies applied the multivariate analysis sanitary hazard index to prioritize remedial actions and assessed the resulting impact.…”