Abstract: An electrode-type water heater or steam generator constructed from only three different manufactured parts includes an electrically non-conductive housing formed from a pair of complementary identical open-face housing sections. The housing sections each have a plurality of spaced grooves on the interior surface thereof and a port in one end wall. One of the housing sections is inverted and secured face-to-face to the other housing section to form a hollow housing having an inlet port in one end, an outlet port in its other end and a series of spaced, parallel, continuous grooves on its inner surface. A plurality of identical disk-shaped carbon electrodes are each supported in a different one of the continuous grooves and are apertured to allow flow of water through the housing from the inlet port to the outlet port.