This study assesses the efficiency of using cold plasma technology to treat groundwater for the purpose of domestic water supply. Experimental results showed that cold plasma was an effective method to remove E. coli in water. After treatment with cold plasma, the concentration of E. coli decreased significantly. In addition, cold plasma greatly reduced iron and arsenic levels. However, the performance of removing arsenic by cold plasma was increased with the presence of ferrous and ferric ions. Chloride, permanganate index, electrical conductivity and pH of groundwater samples were slightly changed after treatment with cold plasma. One of the disadvantages of cold plasma is that it significantly increases nitrate concentration. The effectiveness of water treatment decreased with water flow rate, and increased with time to retain water in the effluent tank. All quality parameters of groundwater samples treated by the prototype have met the Vietnamese standard and WHO guidelines.