An electrochemical water treatment apparatus, for electrical connection to a power supply, and for connection to a source of water to be treated, the treated water thereafter being permitted to flow to a destination, the apparatus comprising: a treatment chamber formed by at least one wall and having a length, an inlet end and an outlet end, and at least one side, the treatment chamber having an opening formed along the side for substantially the length of the treatment chamber; a mounting plate covering the opening, so as to seal the side of the treatment chamber and prevent water to be treated from escaping via the opening; at least three cathodes, each cathode having two ends, and each cathode mounted to the mounting plate and positioned inside the treatment chamber; at least two anodes, each anode having two sides and two ends, and each anode mounted to the mounting plate and positioned inside the treatment chamber, each of the anodes having at least one of the cathodes positioned on each of the two sides of the anode; a first anode bus bar connectable to the power supply and connected to each of the anodes near one end of the anodes and a second anode bus bar (24a-1) connectable to the power supply and connected to each of the anodes near the other end of the anodes, opposite to where the first anode bus bar is connected to the anodes; a first cathode bus bar connectable to the power supply and connected to each of the cathodes near one end of the cathodes and a second cathode bus bar (24b-1) connectable to the power supply and connected to each of the cathodes near the other end of the cathodes, opposite to where the first cathode bus bar is connected to the cathodes, characterized in that the apparatus comprises: an inlet adapter having a first end and a second end, for connecting the treatment chamber inlet end to the source of water to be treated, the inlet adapter having a smaller cross sectional area at the first end connected to the treatment chamber inlet end, and having a larger cross sectional area at the second end connected to the source of water to be treated; and an outlet adapter having a first end and a second end, for connecting the treatment chamber outlet end to the destination, the outlet adapter having a smaller cross sectional area at the first end connected to the treatment chamber outlet end, and a larger cross sectional area at the second end connected to the destination. a treatment chamber formed by at least one wall and having a length, an inlet end and an outlet end, and at least one side, the treatment chamber having an opening formed along the side for substantially the length of the treatment chamber; a mounting plate covering the opening, so as to seal the side of the treatment chamber and prevent water to be treated from escaping via the opening; at least three cathodes, each cathode having two ends, and each cathode mounted to the mounting plate and positioned inside the treatment chamber; at least two anodes, each anode having two sides and two ends, and each anode mounted to the mounting plate and positioned inside the treatment chamber, each of the anodes having at least one of the cathodes positioned on each of the two sides of the anode; a first anode bus bar connectable to the power supply and connected to each of the anodes near one end of the anodes and a second anode bus bar (24a-1) connectable to the power supply and connected to each of the anodes near the other end of the anodes, opposite to where the first anode bus bar is connected to the anodes; a first cathode bus bar connectable to the power supply and connected to each of the cathodes near one end of the cathodes and a second cathode bus bar (24b-1) connectable to the power supply and connected to each of the cathodes near the other end of the cathodes, opposite to where the first cathode bus bar is connected to the cathodes, characterized in that the apparatus comprises: an inlet adapter having a first end and a second end, for connecting the treatment chamber inlet end to the source of water to be treated, the inlet adapter having a smaller cross sectional area at the first end connected to the treatment chamber inlet end, and having a larger cross sectional area at the second end connected to the source of water to be treated; and an outlet adapter having a first end and a second end, for connecting the treatment chamber outlet end to the destination, the outlet adapter having a smaller cross sectional area at the first end connected to the treatment chamber outlet end, and a larger cross sectional area at the second end connected to the destination. an inlet adapter having a first end and a second end, for connecting the treatment chamber inlet end to the source of water to be treated, the inlet adapter having a smaller cross sectional area at the first end connected to the treatment chamber inlet end, and having a larger cross sectional area at the second end connected to the source of water to be treated; and an outlet adapter having a first end and a second end, for connecting the treatment chamber outlet end to the destination, the outlet adapter having a smaller cross sectional area at the first end connected to the treatment chamber outlet end, and a larger cross sectional area at the second end connected to the destination.