I've been doing alot of utility digging lately. Thought I would throw the APWA color code out there.......RED: electric power lines, cables, conduit and lighting cables. YELLOW:Gas, oil, steam petroleum or gaseous materials. ORANGE: communication, alarm or signal lines, cables or conduit. BLUE: potable water. PURPLE: reclaimed water, irrigation and slurry lines. GREEN: sewers and drain lines. WHITE: proposed excavation. PINK: temporary survey marking.