Utility Marking Colors Explained: The APWA Color Code
Colored flags in a yard, spray painted lines across a parking lot: those marks are a standardized language. Every color identifies one type of underground utility, following the uniform color code published by the American Public Works Association (APWA). Utility companies, 811 locators, and private locating crews across the United States all mark with the same system, so an excavator can read any site the same way.
Here is what each utility marking color means, who places the marks, and, just as important, what the colors do not tell you.
The APWA uniform color code
| Color | What it marks | Typical lines |
|---|---|---|
| Red | Electric power lines | Distribution cable, conduit, lighting circuits |
| Yellow | Gas, oil, steam | Natural gas mains and services, petroleum, other flammables |
| Orange | Communication | Telephone, fiber optic, cable television, alarm and signal lines |
| Blue | Potable water | Water mains and service lines for drinking water |
| Green | Sewer and drain | Sanitary sewer, storm drain lines |
| Purple | Reclaimed water | Reclaimed water, irrigation and slurry lines (everywhere in Florida) |
| Pink | Temporary survey markings | Survey control points, unknown or unidentified facilities |
| White | Proposed excavation | The outline of where digging will happen, marked by the excavator |
What do white markings mean?
White paint or white flags are the one color the excavator places, not the utility. White marks outline the proposed excavation area before locators arrive, so each utility company knows exactly where to search. Pre-marking in white is strongly encouraged in Florida: it speeds up locates and reduces missed lines on large parcels.
What do pink markings mean?
Pink is for temporary survey markings and for facilities a locator found but could not identify. If you see pink on your site, treat it as a question mark in the ground. It often means an unknown line exists and needs further investigation before anyone can dig safely near it.
Who places the marks?
After you contact 811, each utility company sends its own locator (or a contract locating firm) to mark the lines it owns, using flags in soft ground and paint on pavement. Marks placed through 811 cover public utilities only, up to the meter or service point. On private property, everything beyond that line, from irrigation to the sewer lateral, is only marked if you hire a private utility locating crew. The colors mean the same thing either way.
Reading the marks: offsets, width, and abbreviations
- The mark is a centerline, not a boundary. Florida's tolerance zone extends 24 inches on each side of the mark. Hand dig inside that band.
- Width callouts: a number in inches next to the line (for example "W 12") gives the width of the buried structure, such as a duct bank or conduit package.
- Owner initials: letters identify the utility company, so damage or questions can be routed to the right operator fast.
What the colors do not tell you
No utility marking color tells you depth. Paint and flags show approximate horizontal position only. Florida sand shifts, grades change, and decades of repairs move lines far from their original burial depth.
The color code also says nothing about unmarked private lines or abandoned pipe, both common on older Florida properties. When depth or completeness matters, the marks get verified with ground penetrating radar and, for high-risk crossings, soft-dig potholing. Our guide on how deep utility lines are buried shows why the depth question deserves its own answer.
When can flags be removed?
Leave utility flags and paint in place until the excavation is finished. Homeowners can remove flags once the work they were placed for is complete, but never before digging starts, and never on an active construction site. If marks fade or get disturbed mid-project, request a re-mark before continuing.
See marks you don't understand?
If your site is painted in colors that do not add up, or you suspect lines that were never marked at all, that is exactly the gap our underground utility locating service closes. We locate public and private lines statewide and mark everything to the same APWA color code your crew already reads. Request a locate to get a Florida technician on site.