No swimming pool shall be built, constructed, erected or maintained nearer to the side lines than five feet on a thirty-foot-wide lot and seven feet on a forty-foot-wide lot and, for all other lots greater than 40 feet in width, nearer than 10 feet to the side lines or rear line of the lot upon which it is located or closer to the front line than the existing allowable setback of the main building. On any corner lot, no swimming pool shall be built, constructed, erected or maintained nearer the street line than the present allowable existing distance for other structures thereon or allowable thereon.