Arsenic pollution of groundwater and water supply by purification of pond water in Bangladesh

Arsenic-contaminated groundwater has been found in 59 districts (as of January 1999) out of a total of 64 districts in Bangladesh where almost all drinking water is supplied from groundwater. The cause of arsenic contamination of groundwater is not clear yet, and it is estimated that about 40 million people are at risk of arsenic poisoning accordingly. The arsenic-free water supply system is, therefore, urgently needed in Bangladesh. Since March 1997 we have been investigating the causes of the arsenic contamination in groundwater and developing arsenic-free water supply systems by using the water in ponds, namely, a Pond Sand Filter system (“PSF” hereafter) in Samta village of Jessore district, which we have chosen as a model village for our research. Prior to the construction of PSF, arsenic, though at low levels, was found in the half of the ponds surveyed. PSF was completed at the end of January 1999. This paper shows the results of our investigations on arsenic pollution of pond water together with that of groundwater and the quality of the treated water by PSF.