Before you dig, excavate, or drill on any property, you need to know what's underground—gas lines, water mains, electric cables, and fiber optics don't announce themselves. The utility locating process protects your crew, prevents costly damage claims, and keeps essential services running. Understanding the timeline from your initial request to the final mark-out ensures your project stays on schedule and compliant.
The 811 Request: Your Starting Point
The process begins when you contact 811 (or your state's equivalent damage prevention hotline) or a private locating service. This is a free or low-cost step: you provide your property address, project scope, and preferred marking date. Most 811 centers are open 24/7, so you can submit requests online, by phone, or through mobile apps.
The clock starts immediately. State regulations typically require locates to be marked within 2–7 business days from request date, though this window varies. If you need marks sooner—say, within 24–48 hours for emergency repairs or critical projects—you'll likely need to hire a private utility locating company, which can cost $150–$400 depending on property size and complexity.
Information You'll Need Ready
When you call or submit your request, have these details available:
- Property address (street number, city, state, zip)
- Project description (what you're doing: building, trenching, boring, etc.)
- Digging area boundaries (mark the perimeter with white paint or flags beforehand)
- Desired mark-out date and time window
- Your name and contact information
- Any known utilities (helps locators prepare)
Providing clear, accurate information speeds up the entire timeline. Vague requests or unmarked dig areas can delay locators or force them to reschedule.
The Locate Request Processing (Day 1–2)
After you submit, the 811 center logs your request and notifies all utility operators in your area—electric, gas, water, sewer, telecommunications, and cable companies. Each operator decides whether their lines are in the project zone. If they are, they add a locate visit to their schedule.
During this phase, expect outbound calls or texts confirming your request details. Some states also issue a locate request number—save this for your records. You'll reference it if you need to reschedule or follow up.
The Mark-Out Visit (Day 2–7)
On your scheduled date, locators arrive with specialized equipment to identify and mark underground utilities. The process typically takes 1–4 hours depending on property size and line complexity. A 1-acre residential lot might take 45 minutes; a 5-acre commercial site could take 3 hours.
Here's what happens on-site:
- Visual inspection for surface clues (valve covers, pull boxes, utility boxes)
- Ground-penetrating radar (GPR) or electromagnetic detection to trace buried lines
- Marking with spray paint in color-coded stripes: red (electric), yellow (gas), blue (water), green (sewer/drain), white (proposed excavation area), pink (temporary), orange (communication)
Locators mark the approximate centerline of each utility. It's crucial to understand these marks show general location, not exact depth or precise boundaries. Depth can vary within the marked area.
After the Mark-Out: Your Responsibilities
Once marks are in place, you have 3–10 days (varies by state) before they fade or become invalid. Begin digging cautiously within 24–48 hours. Hand-dig or vacuum excavate around marked lines—never assume a marked line is deeper than it actually is.
If marks are unclear, faded, or you can't locate a utility you expected, contact the locating service for a re-mark. Most services won't charge if marks are genuinely missing, though re-marks requested due to project delays might carry fees ($25–$75).
Cost Expectations
- 811 call-in (public request): Free–$25
- Private 24–48 hour expedited locate: $150–$400+
- Large or complex projects (10+ acres, multiple operators): $300–$600
- Re-marks due to unclear first marking: Free–$75
Frequently Asked Questions
Q: What if I call 811 but then delay my project by two weeks—do I need to call again? Yes. If your dig date extends beyond the mark validity window (typically 3–10 days), request a fresh locate. Marks fade, and utility locations can change.
Q: Can I dig right up to the paint line, or should I leave a buffer? Always leave a buffer. Painted centerlines can be off by several feet, especially for wide trenches. Hand-dig or vacuum excavate at least 2 feet on either side of marked lines.
Q: Are private utility locating companies faster and more accurate than 811? Private locators offer faster service (24–48 hours vs. 2–7 days) and sometimes higher accuracy, but cost $150–$400. Use them for time-sensitive or critical projects where 811's timeline doesn't fit your schedule.
Find trusted utility locating and 811 service providers on Mercoly to compare response times, pricing, and customer reviews.