The suitable designs of tap water filter (local manufactured) work by plasma technique (corona discharge) was illustrated in more details. The present work show the influence of corona discharge type in the present of magnetic field and magnetic field configurations on the physical properties of tap water which represent the PH value, conductivity and Total Dissolved Solids (TDS) were studied. In this work, the physical properties of tap water that treated by using the electromagnetic filter were tested in the laboratory. The properties of the tap water that treated in this type of filters show that the corona discharge type in the present of both magnetic field configurations has influence on the physical properties of treated tap water. The influence of corona discharge type has limited effect on the physical properties of tap water in the absent of magnetic field. Furthermore, the influence of magnetic field configurations on the physical properties of tap water was studied too. The results of the laboratory test of treated tap water show that the TDS and water conductivity were reduced when the closed magnetic field configuration was applied in the present of both corona discharge types with further reduced when the negative corona discharge is present compare with positive corona discharge.