What are those colored flags in the ground?

Are you new to underground utilities? A homeowner? Or just curious about what those colored flags in the ground are? We have the answers for you. The APWA (American Public Works Association) color codes indicate which utilities lie below. Each marker lets the person above the ground understand which utility is below the ground, making it easier to detect for maintenance and excavating. Utility lines could be inches to feet below the surface, which means calling 811 before you dig is extremely important for everyone’s safety.


How does the utility marking colors work? It’s simple. First, call 811 before you dig. Then a locator arrives on site to detect the trace wire system installed with buried utilities. The locator marks the location of the tracer wire (buried utilities) with colored flags.


  • Orange is telecommunication (phone and internet)
  • Blue is water (potable water)
  • Green is sewer (sanitary and storm sewer)
  • Purple is reclaimed water (irrigation)
  • Yellow is gas
  • Red is electric (power lines)
  • White is a pre-marker. White marks the outer limits for excavating for the suggested installation of buried lines.
  • Pink is a temporary survey marker


The site is now ready for digging/excavation. You can expect to see these flags year-round, but mostly in the non-wintery months. Understanding markers is important not only to utility locators but also to the public. Knowing the importance of the flags and leaving them in place is critical for your safety and the safety of others around you. Download the APWA color codes for a reminder of which colors are designated for which utilities. (Simply select and save the image above.)

lifetime of the utility.