Coatings are described to improve the performance of cathodic protection systems used in water heater tanks. Semi-permeable sparingly soluble films of silicates and other organic resins protect critical areas of sacrificial anodes from concentrated usage which could sever their tank connections, yet preserve the total amount of protection available. They reduce usage of these more active anode areas and return them to service after less active ones are used up, and when the corrosion rate of exposed metal in the tank has been reduced by prolonged service, thus further extending anode life. Other coatings reduce usage of the entire anode in high conductivity waters and in electric heaters where such protection is rapidly consumed by secondary chemical reactions or absorbed by electric heating elements. These coatings also prevent complete deactivation of the anode by oxides, and bacterial interactions which generate objectionable odors. They lessen contamination of tank water by insolubilizing anode byproducts, which are then electroplated onto nearby exposed steel to passivate it, further enhancing anode life. Coatings provide a "time released" protection by exposing fresh anode metal as they dissolve. They are applied either to the anode alone, or to both anode and exposed steel, or anode and electric heating element to increase their effectiveness. Such coatings also reduce anode usage by increasing its electrochemical efficiency which then allows less metal or lower cost alloys to be used for tank protection.