811 Call Before You Dig: Complete Guide
Call 811 before any excavation, including hydrovac. Here's how the national one-call system works, what it does and doesn't cover, and how to follow up correctly.
How 811 Works
811 is the national call-before-you-dig number, and state law requires the call. You contact your state's 811 program — typically by phone or web portal — and provide the dig location and timing. The 811 center notifies all member utilities that have buried infrastructure in the area, and each utility sends a locator to mark their lines on the ground with paint and flags.
Notice Periods by State
Most states require about 2 business days of advance notice before excavation (often written as 48 hours). Some require 72 hours or 3 business days, and a few require more. Always check the specific notice period for the state where work occurs — Hydrovac Hotline's city pages display this for every US state.
What 811 Marks
811 only marks utilities owned by member companies — typically natural gas, electric, water, sewer (sometimes), and major telecommunications/cable lines. Member coverage varies by state. The marks indicate approximate horizontal location only; depth is not provided by 811 markings.
What 811 Does NOT Mark
- Private utilities (irrigation, low-voltage lighting, private sewer laterals)
- Lines owned by non-member utilities (in some states)
- Service laterals from the meter to the building
- Anything on private property where the utility ends at the right-of-way
- Abandoned lines that are no longer in service records
For comprehensive utility location, pair 811 with a private utility marking service. See our utility locating guide.
Color Code Standards
The American Public Works Association (APWA) uniform color code is used nationwide:
- Red — electric power
- Yellow — gas, oil, steam, petroleum
- Orange — communication, alarm, signal lines
- Blue — potable water
- Green — sewer and drain
- Purple — reclaimed water, irrigation
- Pink — temporary survey markings
- White — proposed excavation
Frequently asked questions
How long are 811 markings valid?
Markings are typically valid 14–21 days depending on state. Re-mark requests are required if work extends beyond that window. Marks fade quickly in rain and traffic — protect them or be ready to call for a re-mark.
Is calling 811 free?
Yes — 811 is free for the requester. Member utilities fund the system through fees. Failing to call before excavation can result in fines and full liability for any utility damage that follows.
Does 811 cover private property?
Partially — 811 marks utilities owned by member companies, even on private property, up to the meter. Lines past the meter (irrigation, private sewer, low-voltage) are NOT covered by 811 and require private utility marking.
What happens if I dig without calling 811?
You assume full liability for any utility damage. Civil penalties vary by state but can reach $10,000+ per incident, plus the actual repair costs. Strikes on gas lines can also trigger criminal charges in some jurisdictions.
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