Inequitable allocation of deep community wells for reducing arsenic exposure in Bangladesh

Abstract

Community wells that extend deeper than most private wells are crucial for reducing exposure to groundwater arsenic (As) in rural Bangladesh. This study evaluates the impact on access to safe drinking water of 915 such intermediate (90–150 m) and deep (>150 m) wells across a 180 km2 area where a total of 48,790 tubewells were tested with field kits in 2012–13. Half the shallow private wells meet the Bangladesh standard of 50 µg/L for As in drinking water, whereas 92% of the intermediate and deep wells meet the more restrictive World Health Organization guideline for As in drinking water of 10 µg/L. As a proxy for water access, distance calculations show that 29% of shallow wells with >50 µg/L As are located within walking distance (100 m) of at least one of the 915 intermediate or deep wells. Similar calculations for a hypothetical more even distribution of deep wells show that 74% of shallow wells with >50 µg/L As could have been located within 100 m of the same number deep wells. These observations and well-usage data suggest that community wells in Araihazar, and probably elsewhere in Bangladesh, were not optimally allocated by the government because of elite capture.

Provision of well-water treatment units to 600 households in Bangladesh: A longitudinal analysis of urinary arsenic indicates fading utility

“…Unfortunately, this approach will often fail in Bangladesh because levels of iron are too low and levels of phosphate are too high (Neumann, Kaegi et al 2013). This failed attempt to reduce exposure by treatment at the household-level confirms that well-testing and exploiting the spatial variability of As levels in well-water thus redirecting households to a subset of safe wells, in parallel with more installation of deep community wells, are more promising avenues that need to be reinvigorated in Bangladesh (Ahmed, Ahuja et al 2006, van Geen, Ahmed et al 2014, van Geen 2015). …”

Vulnerability of low-arsenic aquifers to municipal pumping in Bangladesh

“…Using a range of retardation factors from 14 to 20 under, current (local) conditions, we estimate the average downward movement of the high-As zone in eastern Araihazar conditions to be 2–5 cm/yr, although it is likely to be higher in western Araihazar, closer to the pumping center. This moderate rate of contamination helps explain why no wide-scale contamination of low-As aquifers >90 m deep over time has been documented to date in Araihazar or much of Bangladesh (van Geen et al, 2007; 2015; Ravenscroft et al, 2013; 2014). …”

Evidence for Elevated Levels of Arsenic in Public Wells of Bangladesh Due To Improper Installation

“…The documented rate of failure, which is remarkably low given inherent weaknesses in the design of the joints, is likely to be robust given the particularly large pool of wells from which outliers were drawn on the basis of anomalies in As. A far more significant issue than the occasional failure due to a leak in terms of access to safe water in the region is the recently documented geographic clustering of community wells resulting in villages being provided with numerous deep community wells and others that are equally affected none at all (van Geen et al, 2015). …”

“…In such situations, not only the water within the well but also a sizeable portion of the aquifer tapped by the screen could become contaminated over time. Give that As mitigation efforts in Bangladesh remain inadequate with over 40 million villagers still exposed (BBS/UNICEF, 2015), it is important to distinguish technical and engineering issues from other social and political factors that have also limited the impact of on-going installations of deep wells throughout the country (Johnston et al, 2014; van Geen et al, 2015). …”

“…As part of this survey, a total of 927 wells claimed to be over 90 m deep by their caretaker, owner, or local users were recorded and tested for As with a field kit (van Geen et al, 2015). We report here the outcome of further investigation of 9 community wells, the only ones identified during the blanket survey of the region that were confirmed to be >90 m deep and elevated in As.…”