Constant exposure to groundwater contaminated by arsenic (As) constitutes a major health risk for millions of people worldwide. Therefore, the biogeochemical and physical processes responsible for the release, transport and retardation of As in groundwater need to be identified to optimize groundwater management strategies, both in rural and urban areas. River delta regions in Asia constitute a relevant spot to study the presence of As in drinking water, due to the interplay among the natural release of As from sediments, the onset of redox fronts in aquifers, which can sharply change the mobility of As, and the anthropogenic increased groundwater extraction for the supply of growing urban areas. The AdvectAs project involves several teams to promote transdisciplinary research on the environmental behaviour and spatial heterogeneity of As in groundwater under advective conditions associated with extensive pumping of pristine groundwater from the city of Hanoi, Red River delta region in Vietnam. In autumn 2017 a sampling campaign in the vicinity of Hanoi was carried out, integrating sediment analyses, geochemical, mineralogical and microbiological studies, hydrogeochemical characterization of groundwater, groundwater dating and transport modelling. The first outcomes of the hydrogeochemical analyses will be presented in this contribution.