Since urban water supply is not yet available for every inhabitant in Hanoi City, numerous residents look for alternative sources such as groundwater and rainwater to compensate the supply shortage. However, in parts of Hanoi, it was reported that groundwater is polluted by various contaminants including arsenic (As) and ammonia (NH4-N). Therefore, numerous types of point-of-use (POU) water treatment systems have been used in households, but treatment efficiency has not been well documented. Hence, this study aims to investigate the proliferation and efficiency of household treatment systems. One hundred and seventy households from three communes were selected for a survey of questionnaires and face-to-face interviews. Twenty-four household water treatment systems from six communes were monitored for water sample collection and analysis. The results indicate that sand filter (SF), ceramic filter (CF), microfiltration (MF), anion exchange (AX) and reverse osmosis (RO) were popular POU water treatment systems, but removal efficiency varied among different treatment processes. Groundwater quality shows an average As concentration of 71 μg/L (max. 305 μg/L) and 81% of these samples had As concentration higher than the World Health Organization guideline value of 10 μg/L. An integration of SF and RO can guarantee water with As concentration below 10 μg/L, whereas AX, MF and CF did not remove As at all.