Where alleys are not provided, easements of not less than five feet in width shall be provided on each side of the rear line or side line for necessary utility lines, wires, conduits, storm and sanitary sewers, gas and water. Easements of the same or greater widths may be required along boundary lines or across lots or parcels where necessary for the extension of utility lines, waterways, and walkways, and to provide necessary drainage ways or channels.