An electrocoagulation reactor for the treatment of wastewater. The electrocoagulation reactor typically engages a DC power source and a source of wastewater to be treated. It has a housing with walls and a wastewater inlet, and a treated wastewater outlet. There is at least one anode/cathode pair of oppositely charged spaced apart plates that engage the power source to charge the anode with a positive charge and the cathode with a negative charge. Between each anode/cathode pair is at least one segmented intermediate plate, which is not engaged to the power source of electrical energy, and which intermediate plate is segmented into multiple segments, which multiple segments lay generally in the same plane.