White
Commonly used to show the proposed excavation area or work zone.
Marking Colors
What color are septic or sewer line markings?
Utility paint and flags can be helpful, but they are easy to overread. Green markings commonly point to sewer or drain-related utilities, but that does not automatically prove your private septic tank, septic lines, or drain field have been marked.
- Green is commonly associated with sewer and drain lines
- White often marks the proposed excavation area
- Paint does not always include private septic components
- Marks usually show approximate location, not full depth
Green markings
Often indicate sewer, drain, or similar wastewater-related utility markings.
Not a guarantee
Green paint does not automatically mean the private septic tank or drain field was located.
Next step
Compare markings with records, tank clues, and your planned dig area before digging.
Color Guide
Common utility marking colors homeowners may see
Color standards are meant to make marks easier to interpret, but the marks only cover what the locator actually marked.
Green
Commonly associated with sewer and drain lines. It may not include private septic components.
Red
Commonly associated with electric power lines, cables, conduit, or lighting cables.
Yellow
Commonly associated with gas, oil, steam, petroleum, or gaseous materials.
Orange
Commonly associated with communications, alarm, signal, cable TV, or fiber lines.
Blue and purple
Blue is commonly associated with potable water. Purple is commonly associated with reclaimed water, irrigation, or slurry.
Septic Caution
Why marking colors do not fully answer the septic question
When you call 811, member utility operators mark facilities they own or operate. Private septic tanks, septic lines, drain fields, and owner-side wastewater components may not be part of that response.
Green marks may identify a sewer or drain-related facility, but a private septic system can still be unmarked. If your project depends on knowing the tank, line, or drain field location, use records and septic-specific clues before relying on paint alone.