To prevent corrosion of the circular bottom of a storage tank, several small cylindrical anodes are placed beneath and parallel to the tank bottom, and parallel to each other. A design strategy is presented for determining the anode spacing and depth for proper cathodic protection. For a uniform flux density of oxygen to the tank bottom, the maximum potential variation on the tank bottom (made dimensionless with the average cathode current density, the soil conductivity, and the anode spacing) is reported along with estimates of the potential drop in the soil between the cathode and the anodes and the potential drop within the anodes themselves.