An apparatus (20) for treating contaminated water has an electrocoagulation reactor (26) and a clarifier (30) to receive the effluent of the reactor. The reactor has a reaction vessel (48) having an inlet (58) and an outlet (62), a sacrificial anode (64), a rotatable cathode (68) and a non-sacrificial anode (66). A first gap (70) between the sacrificial anode and the cathode comprises a first water treatment zone. A second gap (74) between the cathode and the non-sacrificial anode comprises the second water treatment zone. The water flow path is from the inlet to the first treatment zone, then to the second treatment zone and then to the outlet. In the clarifier, the reactor effluent is separated into cleaned water and the contaminated sludge.
