s pat no 4 848 616 which is herein fully incorporated by reference the method of the invention comprises applying a diamond like coating to the surface of the heating element employing a dlc coated heating element provides a method of minimizing galvanic corrosion the dlc is electrically resistive or electrically insulating and insulates the heating element from other metals in contact with the water therefore the dlc coating reduces galvanic current flow between the metals which in turn minimizes galvanic corrosion to practice the invention the shape and size of the heating element is not critical and conventional heating elements may be employed such as those well known in the art see for example fig1 and 2 of u s pat no 5 878 129 to jackson which is herein fully incorporated by reference customary heating elements include an electrical wire an electrically insulating layer surrounding the electrical wire and a sheath surrounding the electrically insulating layer thus the outer surface of the sheath is the surface of the heating element the sheath is usually a corrosion resistant metal preferably the heating element is a water heater element turning to the diamond like coating these coatings are carbon based films which may be produced by a variety of ion beam and plasma techniques such as low energy carbon ion beam dual beam ion plating techniques and rf sputtering or rf and dc plasma deposition of a hydrocarbon gas such as acetylene or other alkanes for a more detailed discussion.