When is it worth hiring a private underground utility locator instead of relying solely on 811?

Short answer

Hire a private underground utility locator any time you need markings for anything beyond public utilities, you’re digging near the house or beyond the meters, you’ll use mechanical equipment, or you’re unsure of what’s in the ground. Call 811 first for public utilities, then bring in a private locator to find private lines like sprinkler pipes, yard lighting, gas to a grill or pool heater, septic, well lines, and power to sheds—none of which 811 typically marks.

Why 811 isn’t enough

811 coordinates locates for public utility-owned lines, usually up to the meter or termination point:
- Power, gas, water, sewer, and communications to the meter/point of service
- Public mains in the street and often to the curb/ROW

What 811 typically does not mark:
- Any line on the property after the meter: electric to garages/sheds, pool power, landscape lighting, propane lines from tank to house/appliance
- Irrigation pipes and control wires
- Private water/sewer laterals, well lines, septic tanks and laterals
- Low-voltage runs (cat cable, security, audio)

A private locator fills this gap and can use EM locators, GPR, and tracing methods to identify both metallic and non-metallic utilities on your side of the meter.

Situations where a private locator is worth it

• You’ll be trenching, augering, stump grinding, or running a skid steer/excavator
• You’re digging near the house, between meter and structure, or near outbuildings
• Older properties with unknown renovations or previous owners’ DIY work
• Irrigation-heavy yards, pools, hot tubs, or propane tanks
• Rural properties with wells/septic where maps are scarce or outdated
• Conflicting or sparse 811 marks, or lines that don’t make sense
• Commercial/HOA campuses and schools with private campus utilities
• Non-metallic utilities (PVC water/irrigation) where GPR is needed

Step-by-step: How to do it right

1. Call 811 first
   • Request locates 2–3 business days before digging (lead time varies by state).
   • Sketch and mark your proposed dig area with white paint/flags.
2. Review the 811 marks
   • Check for completeness and color codes (see Safety section).
   • If gaps exist or you have private systems, move to step 3.
3. Hire a private locator
   • Ask for providers who offer both EM locating and GPR.
   • Provide site info: age of home, renovations, utilities you know of, proposed excavation path.
   • Ask for deliverables: marked lines, a sketch/map, photos, and depth estimates (depths are approximate).
4. Daylight critical crossings
   • Before mechanical equipment, expose utilities by hand or vacuum excavation along your trench path to verify location and depth.
5. Maintain marks
   • Re-mark if rain/traffic fades paint. Many locates expire in 10–21 days.

Tools and materials

• Marking and layout
  • White marking paint/flags for proposed dig area
  • APWA color flags/paint for utilities (pros will mark): red, yellow, orange, blue, green, purple
• Exposure and hand digging
  • Non-conductive shovel (fiberglass handle), trenching shovel, drain spade
  • Hand trowel, soil probe rod
  • Shop vac with hydro-excavation attachment or rental vacuum excavator for safe daylighting
• Locating gear (used by pros; also available in the ToolStash catalog)
  • Electromagnetic pipe & cable locator with transmitter/clamp (e.g., SeekTech/NaviTrack style)
  • Ground Penetrating Radar (GPR) cart for non-metallic utilities
  • Ferrous magnetometer and valve/box locator for buried valves and tanks

Safety and best practices

• Respect tolerance zones

Typical tolerance zone: 18–24 inches horizontally on either side of the locate mark. Depth is NOT guaranteed.
Only hand-dig or vacuum-expose within the tolerance zone.

• Know the color code (APWA):
  • Red: electric
  • Yellow: gas/oil/steam
  • Orange: communications
  • Blue: potable water
  • Green: sewer/drain
  • Purple: reclaimed/reuse/irrigation
  • Pink: temporary survey
  • White: proposed excavation
• Never assume depth. Frost, grading changes, and past work can change cover depth.
• Shut off sprinkler zones and mark visible heads/valves before locating to avoid damage.
• If you hit or nick a line, stop work and contact the utility or 811 emergency.

Tips for best results

• Schedule locates several days ahead; allow time for both 811 and private locator visits.
• Share any site plans, as-builts, or photos with the locator. Even partial info helps.
• Request both conductive (direct connect/clamp) and inductive tracing where possible.
• For PVC water/irrigation, ask the locator about tracer wire methods or GPR passes.
• Photograph and measure from fixed landmarks (corners of house, fence posts) to preserve the locate record for future projects.

Common mistakes to avoid

• Assuming 811 marked everything past the meter or on private property
• Relying on depth readouts as exact—treat all depths as estimates
• Using mechanical equipment before daylighting crossings
• Forgetting secondary lines: yard lights, low-voltage, pool, grill, shed power
• Letting marks fade or expire; not requesting a refresh after rain

Cost and timing

• Private residential locate: $200–$600 for typical lots; complex/GPR-heavy jobs $300–$800+
• Vacuum daylighting: $150–$300 per hour (contractor); DIY hydro-vac attachments are cheaper but slower
• Time on site: 1–3 hours for most homes; larger or complex sites may take half a day

When to call a pro

• Any mechanical excavation (trenching, augers, stump grinders)
• Non-metallic utilities suspected (PVC irrigation, plastic water lines)
• Properties with propane tanks, wells, or septic
• Conflicting or unclear 811 marks
• Commercial/large residential with multiple outbuildings

Bringing in a private locator after 811 gives you a fuller picture of what’s underfoot, reduces risk, and often saves money by preventing repairs and delays. For many backyard projects, that extra $200–$500 is cheap insurance against a severed cable, flooded trench, or worse.