At a glance
The short version
- Eight colors carry defined meanings under the APWA Uniform Color Code, which is rooted in the ANSI Z535.1 safety color standard.
- White is not a utility. It is the excavator marking out where the work is proposed.
- Pink is not a utility either. It is temporary survey marking.
- Marks show approximate horizontal position. They are not a depth statement, and they expire.
_The paint and flags on a job site are a standardized language. Eight colors, each with a defined meaning, plus a set of conventions for what the marks are actually telling you about position, depth and age._
Where the colors come from
The American Public Works Association maintains the Uniform Color Code for temporary marking of underground facilities, and the code is grounded in ANSI Z535.1, the American National Standard for safety colors. 1Jump to source 12Jump to source 2 The Common Ground Alliance reproduces it in Appendix B of its Best Practices, which is why the same eight colors mean the same eight things whether you are working in El Paso, Las Cruces or three states away. 3Jump to source 34Jump to source 4
APWA encourages public agencies, utilities, contractors, associations and manufacturers to adopt the code, and adoption is broad enough that you should read any departure from it as a question worth asking rather than a local dialect. 2Jump to source 2
The eight colors
| Color | What it identifies |
|---|---|
| White | Proposed excavation — the limits of the work, marked by the excavator. |
| Pink | Temporary survey markings. |
| Red | Electric power lines, cables, conduit and lighting cables. |
| Yellow | Gas, oil, steam, petroleum or other flammable or gaseous material. |
| Orange | Communication, alarm or signal lines, cables or conduit. |
| Blue | Potable water. |
| Purple | Reclaimed water, irrigation and slurry lines. |
| Green | Sewers and drain lines. |
APWA Uniform Color Code for temporary marking of underground facilities. 1Jump to source 12Jump to source 25Jump to source 5
Two of those eight are the ones people most often misread. White is not a buried utility — it is the excavator saying “this is where I intend to dig.” Pink is not a buried utility either — it is survey control. If the only marks on a site are white and pink, nothing has been located yet.
White lining, and why it is worth the paint
Pre-marking the work area in white before the locator arrives is a Common Ground Alliance best practice. The proposed excavation area should be delineated in white paint using a continuous line, dots marking a radius or arc, or dashes marking the corners or outline of the project. Where dashes are used, the guidance puts them at roughly 6 to 12 inches long and about an inch wide, spaced approximately 4 to 50 inches apart. 3Jump to source 34Jump to source 4
Where a site sits inside a radius of 50 feet or less, it can instead be delineated with a single stake at the proposed center — provided the excavator states in the 811 notification that a single center stake was used and gives the radius. 3Jump to source 3
The practical benefit is simple. A locator who can see the work area marks the work area. A locator who cannot has to guess from a text description, and the usual failure mode is a locate that covers the wrong end of a long lot.
Digital alternatives: CGA notes electronic or virtual pre-marking as an alternative to paint. 3Jump to source 3 If you are using it, say so on the ticket so the locator knows what to expect on arrival.
What a mark is telling you — and what it isn’t
A paint line records where a locator interpreted the facility to run, horizontally, at the surface. Read it with three qualifications in mind.
- It is a horizontal indication, not a depth callout — Where a depth is written on the ground, treat it as additional information from the locator about that spot, not as a uniform cover depth along the run. Grade changes, prior regrading and settlement all move cover.
- It carries a tolerance zone — Texas rules define the tolerance zone as half the nominal diameter of the facility plus a minimum of 18 inches on either side of its outside edge, measured horizontally. 6Jump to source 6 The mark is the center of a band, not a hairline.
- It expires — In Texas an excavator who notified between 48 hours and 14 days before starting must re-notify if the start slips beyond 14 days from the original notice. 7Jump to source 7 In New Mexico, excavators must request reaffirmation of line location every ten working days after the initial request. 8Jump to source 8 Old paint is not a current locate.
Colors on a private locate
A private locator uses the same eight colors, for the same reason a second electrician uses the same wire colors: a shared code only works if everyone keeps it. What differs is scope, not vocabulary. Public marks come from member utilities and stop at the point of service; private marks cover the owner’s side of that line — the subject of our guide to what 811 does and does not cover.
On a site with both, expect the colors to be continuous across the meter even though the responsibility for them is not. It is good practice to note on your own site record which marks came from the 811 ticket and which came from a private locate, because they age out on different schedules and answer different questions if something is later damaged.
View 8 numbered sources
Sources
Every numbered claim above traces to one of these. Links go to the publisher of record.
- Uniform Color Code — American Public Works Association — https://www.apwa.org/wp-content/uploads/Uniform-Color-Code-1.pdf
- APWA Guide: Uniform Temporary Marking of Underground Facilities — American Public Works Association — https://www.apwa.org/wp-content/uploads/APWA-Guide_UniformTempMarkingsNEW-V1-02-25-22.pdf
- Best Practices Appendix B — Uniform Color Code and Marking Guidelines — Common Ground Alliance — https://bestpractices.commongroundalliance.com/Appendix-B-Uniform-Color-Code-and-Marking-Guide/Guidelines-for-Excavation-Delineation
- Best Practice 5.02 — Delineate Area of Proposed Excavation — Common Ground Alliance — https://bestpractices.commongroundalliance.com/5-Excavation/502-Delineate-Area-of-Proposed-Excavation
- 811 Utility Color Code Guide — Underground Marking Colors — Texas 811 — https://texas811.org/underground-utility-color-code/
- 811 and Texas Damage Reporting Form (TDRF) handout — Railroad Commission of Texas — https://www.rrc.texas.gov/media/npjpkafo/811-and-texas-damage-reporting-form-handout.pdf Tolerance zone definition.
- Excavator FAQs — Texas One Call requirements and safety — Texas 811 — https://texas811.org/excavator-faqs/
- New Mexico Utility Damage Prevention and Excavation Safety — New Mexico 811 — https://www.nm811.org/
Sourcing and limitations
This guide is original writing by High Desert Scan & Locate, LLC. It cites third-party statutes, standards, codes and publications, all of which remain the property of their respective owners. We describe them in our own words and do not reproduce their text. Standards published by bodies such as ASTM, ACI, ASCE/UESI/CI and PTI are available from those publishers; where one governs your work, obtain the current edition and read it. The published source controls; our paraphrase does not, and an edition cited here may since have been revised or superseded.
No representation or warranty. This material is provided "as is." We make no representation or warranty, express or implied, as to its accuracy, completeness, reliability or currency. It is accurate only as of the review date shown, if at all. Laws, rules and standards change, and we do not undertake to update it.
Not professional advice. Nothing here is legal, engineering, surveying or safety advice, and reading it creates no professional or client relationship. It is not a substitute for a site-specific scope, and it does not clear any area for excavation, cutting or coring.
Company names, product names and trademarks are used for identification only and do not indicate affiliation, sponsorship or endorsement. We receive no compensation for any mention.
Corrections: info@highdesertscan.com. See our Editorial policy, sourcing and attribution.
Private utility locating supplements, and does not replace, public one-call (811) notification. Utility designation is Quality Level B per ASCE/UESI/CI 38-22 unless otherwise stated. GPR interprets subsurface conditions; it does not expose them. Results are interpretations of conditions present within the requested area on the service date, and depend on target material, depth and site conditions.
