TUBEWELL INSTALLATION FOR ACCELERATING SAFE DRINKING WATER ACCESS IN BANGLADESH - HARNESSING LOCAL DRILLERS’ KNOWLEDGE

Regional scale occurrence of natural arsenic (As) in groundwater has impacted safe drinking water access in Bangladesh. Millions of people are exposed to As at levels above the WHO guideline (10 μg/L). Considering the magnitude of the human health impacts and the outcomes of the mitigation programs, the main challenge is to implement a sustainable mitigation program for scaling up safe water access that complies with drinking water safety plan (DWSP). Tubewells as the most widely accepted drinking water option in rural Bangladesh, widely installed at community levels by local drillers using the hand percussion drilling technique. Arsenic is mobilized naturally in groundwater under reducing condition in shallow aquifers (< 50 m) where Fe-oxyhydroxides are reduced releasing As to the groundwater and illustrated by covariation of As and total Fe in groundwater. Since the past decade and half, the local drillers are installing new wells in regions with elevated levels of As targeting the shallow aquifers (< 100 m) based on sediment color to provide As-safe drinking water at relatively low cost. The Project Sustainable Arsenic Mitigation (SASMIT) has followed up the practice of tubewell installations by the local drillers in Matlab, southeastern Bangladesh with an aim to evaluate and validate their simple perspective on water quality based on color of the aquifer sediments. Water quality monitoring in the shallow, intermediate deep and deep aquifer systems through depth-specific piezometers (n=82) installed at 15 locations in Matlab region, over a period of 3 years and a follow-up monitoring during 2015, revealed that the water quality parameters are relatively stable in terms of overall groundwater quality especially As and Mn. The local drillers’ indigenous knowledge on perception of sediment color with validation of water quality monitoring can thus be optimally harnessed for accelerating the drinking water supplies in rural Bangladesh.