A review of arsenic mitigation strategies in community water supplies with insights from South Asia: options, opportunities and constraints

Widespread, geogenic arsenic (As) pollution of groundwater has become a severe constraint for community drinking water supplies in several areas of the world. Despite the availability of numerous traditional and emerging technologies, only a limited number are used for community water supply due to the challenges and constraints for practical solutions, thereby limiting access to clean drinking water to several hundreds of millions of people globally. Here, we have outlined a critical review of several mitigation strategies, including technologies, practices, opportunities, and challenges, thereby trying to bridge the knowledge gap between academic research and field applications. These include widely used ex situ and less common in situ and passive technologies as well as emerging technologies and AI applications. Natural solutions through exploration of hydrostratigraphic heterogeneous As-safe aquifers are also reviewed. We have also provided a review of background influences of in situ (e.g. geography, geology, hydrology) and exogenous (e.g. human behavior) factors that lead to the adaptability of specific As-mitigation strategies. The discussed research gaps and opportunities should help the scientific community to identify future scopes for more efficient safe drinking water supply and distribution in As-affected regions. Further, to bolster the review, introspections and experiences of As mitigation from an extensive network of community drinking water supplies, serving an similar to 80 million population in parts of South Asia (West Bengal, India), regarded as one of the most severely As-polluted parts of the world, are discussed.