By Andrew Clark, SAM, LLC
As Subsurface Utility Engineering (SUE) professionals, we rely on field markings as a primary means of communicating subsurface utility information to designers, surveyors, utility coordinators, contractors, and other project stakeholders. Paint markings are often the most visible—and sometimes the most misunderstood—deliverable we provide in the field. Because of that visibility, the choices we make regarding paint color and marking practices matter more than we sometimes realize.
Across the industry, there is no single, consistent approach to how SUE utilities are marked in the field. Some SUE providers use APWA color-coded paint exclusively, others use a combination of pink paint with color-coded identifiers, and some use pink paint only. Based on my experience, I strongly believe that pink paint is a must when performing SUE investigations. Pink clearly communicates that the markings are not utility owner responses to a one-call (811) request, and that distinction is critical.
A SUE provider is marking utilities for design and planning purposes, not for excavation clearance. There should be no misunderstanding between SUE markings and utility owner markings, yet in practice, confusion happens frequently.
Where Confusion Occurs—and Why It Matters
SUE markings are seen by far more people than just the design team. Surveyors, utility owners, contractors, inspectors, project stakeholders visiting the site, and even the general public encounter these markings. When SUE paint closely resembles 811 markings, it is easy for observers to assume the markings represent utility owner locates—even when that was never the intent.
I have seen this confusion create real issues in the field. In one case, a utility owner did not respond to a one-call request because they believed someone else from their organization had already marked the site—those markings were actually placed by a SUE provider using color-coded paint only. In another instance, a surveyor did not collect SUE markings because they assumed the paint represented standard one-call locates. Neither situation involved negligence; both were the result of understandable assumptions driven by how the markings looked.
These scenarios highlight an important point: paint is a communication tool, and if that communication is unclear, the risk extends well beyond the SUE team.
What Paint Can—and Cannot—Communicate
Paint markings are extremely effective for visualization. They help show that an area has been evaluated beyond a basic one-call response and that additional investigation has occurred. However, paint alone should never be interpreted as representing precise horizontal accuracy, vertical accuracy, utility size, or material. It does not—and should not—convey that level of certainty. Attribute information such as these should be documented, reviewed, and relied upon through formal SUE deliverables—not interpreted from paint in the field.
When paint markings are misunderstood or over-relied upon, they can create false confidence, misinform design decisions, and introduce unnecessary risk into a project. This is especially true when SUE markings are visually indistinguishable from utility owner locates.
Recognizing these limitations underscores the importance of adopting consistent field marking practices that clearly communicate intent without overstating certainty.
Best Practices to Protect the Integrity of SUE Markings
In my opinion, SUE providers should adopt a consistent, intentional field marking process that protects the integrity and intent of the work. A best-practice approach includes:
- Pink paint as the primary marking color to clearly identify SUE work
- Optional color-coded dots or identifiers to supplement (not replace) pink markings
- Use of line identifiers or labeling for quality control and internal verification
- A standardized field process applied consistently across projects and crews
This approach balances clarity for external stakeholders with the internal needs of the SUE team, while reducing the likelihood that markings are misinterpreted as one-call responses.
Standards, Education, and the Path Forward
ASCE 38-22 provides an important framework for SUE, but it is intentionally a general guideline and does not currently address paint color practices in detail. While future revisions of the standard may offer more clarity, the issue today is less about regulation and more about education and professional best practices.
As SUE professionals, we should be proactive in how we communicate our work in the field. Clear, intentional marking practices help protect our data, reduce confusion, and support better outcomes for designers, utility owners, and construction teams alike.
Paint color may seem like a small detail, but in practice, it plays a significant role in how our work is perceived and used. By standardizing our approach and being deliberate in how we mark utilities, we can improve understanding, reduce risk, and strengthen the overall value of SUE on our projects.
APWA / CGA Utility Marking Color Code
Color Utility Type
Red Electric power lines, cables, conduit, and lighting cables
Yellow Gas, oil, steam, petroleum, or gaseous materials
Orange Communication, alarm, signal lines, cables, or conduit
Blue Potable water
Green Sewer and drain lines
Purple Reclaimed water, irrigation, and slurry lines
Pink Temporary survey markings (commonly used by survey and SUE providers)
White Proposed excavation limits or pre-marking