319 1 INTRODUCTION The arsenic problem in Bangladesh has been described as the largest mass poisoning in history (Rahman et al. 2001, Smith et al. 2000) Chronic ingestion of inorganic arsenic causes characteristic skin lesions as observed in populations in Bangladesh and elsewhere. The presence of arsenic above the Bangladeshi limit of safe drinking water (50 µg/L, WHO 2001) was first detected in groundwater of the Bengal Delta Plain (BDP) aquifers in Bangladesh in 1993 (Bhattacharya et al. 1997, 2002, 2004, Nickson et al. 2000, Smedley & Kinniburgh 2002, Ahmed et al. 2004). This has resulted in a severe environmental disaster affecting several million people in the region, as groundwater is the main source of potable water for nearly 98% of the population in Bangladesh. What was a success story is now poised to threaten the lives of millions of people living in 61 out of the 64 districts in Bangladesh (Figure 1). Given the present scenario of safe water status, it would not be possible for Bangladesh as well as other arsenic affected parts of the globe to ensure the target of the Millennium Development Goals of Sustainable safe water options in Bangladesh: Experiences from the Arsenic Project at Matlab (AsMat) Md. Jakariya, Mizanur Rahman, A.M.R. Chowdhury Research and Evaluation Division, BRAC , Dhaka, Bangladesh. Mahfuzar Rahman, Md. Yunus, Abbas Bhiuya, M.A. Wahed International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B): Center for Health and Population Research, ICDDR,B, Dhaka, Bangladesh Prosun Bhattacharya, Gunnar Jacks Dept. of Land and Water Resources Engineering, KTH, SE-100 44 Stockholm, Sweden Marie Vahter Division of Metals and Health, Karolinska Institutet, SE-171 77 Stockholm, Sweden Lars-Åke Persson Department of Women's and Children's Health, Uppsala University, Uppsala, Sweden ABSTRACT: The presence of elevated levels of naturally occurring arsenic in groundwater of Bangladesh, has severely impaired the decade long effort of providing safe water to nearly 98% of its population and putting an estimated 35 million people-nearly one fourth of the total population –at risk. In order to address this problem, a project titled “Arsenic in tubewell (TW) water and health consequences in Matlab Upazila of Chandpur district (AsMat)” is being implemented jointly by ICDDR,B and BRAC. During this study. all the TWs in Matlab have been assigned unique identification numbers, with marked GPS coordinates, depth, and age. It is estimated that nearly 65% of the about 13.000 TWs in Matlab have As concentrations above the Bangladesh drinking water standard (50 µg/L). In order to minimize arsenic exposure, a work to provide various alternate safe drinking water options to the exposed population has been initiated. As of March 2004, about 1,047 different alternate safe water options, such as Pond Sand Filter (PSF), Rainwater Harvester (RWH) and different filters to remove arsenic as well as pathogenic bacteria, were distributed among the targeted exposed population in Matlab. To ensure sustainable use, the provided options were assessed based on community acceptability, technical viability, and financial viability.