Utility color codes are used for identifying existing underground utilities in construction areas with the intent of protecting them from damage during excavation.
Public utility systems are often run underground; some by the very nature of their function, others for convenience or aesthetics. Before digging, local governments often require that the underground systems’ locations be denoted and approved, if it is to be in the public right-of-way.
Colored lines at and/or flags are used to mark the location and denote the type of underground utility. A special type of spray paint, which works when the can is upside-down, is used to mark lines, often in a fluorescent color. On flags, a logo often identifies the company or municipal utility which the lines belong to, or an advertisement for a company which has installed an irrigation system for lawns or gardens. In this case, each sprinkler head is usually marked, so that landscaping crews will not cover or bury them with soil or sod, or damage them with tractors or other construction equipment while digging holes for trees, shrubs, or other large plants or fence posts. This is also important because a vehicle (tractor, truck, or otherwise) can break a sprinkler or the hard-PVC pipe or joint it is mounted on simply by driving over it, particularly on newly-moved soil which is not compacted and therefore unsupportive of such weight.
The American Public Works Association (APWA) Uniform Color Codes for temporary marking of underground utilities are listed below:
Red electric power lines, cables, conduit, and lighting cables
Orange telecommunication, alarm or signal lines, cables, or conduit
Yellow natural gas, oil, steam, petroleum, or other gaseous or flammable material
Green sewers and drain lines
Blue drinking water
Violet reclaimed water, irrigation, and slurry lines
Pink temporary survey markings, unknown/unidentified facilities
White proposed excavation limits or route