Line Locate vs Camera vs Excavate: Yard Leak Decision Matrix

Why this matters

A wet spot in the yard, a water bill that doubled, or a soggy lawn line tells you there is a buried leak; it does not tell you where, how deep, or which line. Three tools answer different questions, and using the wrong one first burns hours and the customer's trust. A camera shows the inside of a drain or sewer but cannot see a pressurized water service. A line locate puts an X on the surface but cannot tell you the pipe is cracked versus a fitting weeping. Excavation finds everything but is the most expensive, most disruptive, and most irreversible step. The job is to spend the minimum to reach a confident dig point, then dig once.

The options

What each method does and its hard limits:

• Line locate (acoustic, tracer wire, or sonde). Acoustic correlators and ground microphones pinpoint a pressurized water leak by sound. Tracer-wire or electromagnetic locators trace a metallic or wire-traced line's path and depth. A sonde (transmitting probe) pushed through a non-metallic pipe lets the locator follow plastic. Answers "where is the line and where is the leak" on pressurized service lines without digging.
• Camera (CCTV) inspection. A self-leveling push or crawler camera runs the inside of a drain, sewer, or large-diameter line. Shows breaks, root intrusion, bellies, offsets, and infiltration. Pairs with a locator-readable sonde at the camera head to mark the surface point above any defect found. Answers "what and where" on gravity drainage lines, not pressurized water.
• Excavation (or potholing). Open the ground at a located point. Potholing (a small confirming dig or vacuum excavation) verifies before committing to a full trench. Answers everything definitively and is the only path to the actual repair, but is the costliest and most disruptive, and demands an 811 utility locate first.

When line locate wins

Lead with a line locate when the leak is on a pressurized water service: a clean-water surfacing leak, a running meter with all fixtures off, or a pressure-loss test that holds the house but bleeds at the meter. Acoustic correlation and ground-mic listening place the leak within a foot or two on metallic or correlatable line. For a plastic service with no tracer wire, push a sonde or use a correlator on the two end fittings. Locate also wins as the first move before any excavation on any line, because you mark the path and depth and avoid the other buried utilities. Signs that point here: continuous meter creep, audible hiss at the meter or a hose bib, and no involvement of drainage.

When camera wins

Lead with a camera when the symptom is drainage, not water supply: recurring sewer backups, a sinkhole or settling over a known sewer run, sewer gas in the yard, or a slow main that snaking does not durably clear. The camera shows the failure mode (root mass, collapsed clay, offset joint, grease, belly) which decides the repair method (spot dig, liner, or full replacement). Crucially, run the camera with a sonde at the head and locate the defect from the surface so the dig point is exact. Camera also wins when you need to prove condition to the customer before quoting a trench. It does not find pressurized water leaks; do not point a drain camera at a service-line problem.

When excavating wins

Go straight to excavation only when location is already known and confirmed, or when non-destructive methods cannot resolve it. Examples: a service line surfacing in one obvious spot with a visible blowout, a sewer the camera proves is collapsed at a sonde-marked point, or a repair that must happen regardless (line replacement, fitting failure at a known coupling). Always pothole or vacuum-excavate to confirm the exact pipe and depth before opening a full trench, and always complete an 811 public-utility locate before any digging. Excavation is the repair step, not a search step; if you are digging to "look for" the leak, you skipped a tool.

Field decision flow

1. Classify the symptom. Clean water surfacing, running meter, lost pressure: pressurized supply path. Sewage, backups, gas smell, settling over a sewer: drainage path.
2. Supply path: isolate at the meter and house valve, confirm the leak is between them, then line-locate (acoustic correlation plus tracer or sonde). Mark and depth the point.
3. Drainage path: run a CCTV camera with a head sonde, find the defect, locate it from the surface, mark and depth the point.
4. Either path, before digging: complete 811, then pothole or vacuum-excavate to verify pipe and depth at the marked point.
5. Excavate the full repair only after the confirming pothole agrees with the located point. Disagreement means re-locate, do not widen the hole hunting.

Two field habits keep this efficient. First, always mark and depth the point, not just an X on the grass; depth determines whether you trench or bore, and an unmarked depth turns a clean dig into an exploratory one. Second, cross-check the locate before committing. On a pressurized line, confirm the acoustic point against the meter-creep evidence and the surfacing water; on a sewer, confirm the camera-and-sonde point by re-running the sonde and re-reading the surface position. Methods can disagree when there are two defects or when a sonde signal bleeds, and digging on a single unconfirmed reading is how a one-hole job becomes three. When the symptom is ambiguous (a soggy area that could be supply or drainage), run the cheap discriminator first: isolate at the meter and watch for creep with all fixtures off. Creep means supply and sends you to a locator; no creep with a wet drainage path sends you to the camera.

References

• Common Ground Alliance Best Practices and the national 811 one-call program for damage prevention and pre-excavation locating.
• AWWA M36, Water Audits and Loss Control Programs, for service-line leak quantification and detection methods.
• Uniform Plumbing Code (UPC) and International Plumbing Code (IPC) provisions on water service and building sewer location, depth, and repair.
• NASSCO Pipeline Assessment Certification Program (PACP) for standardized CCTV defect coding and condition grading.
• OSHA 29 CFR 1926 Subpart P, Excavation, for trench safety and protective-system requirements.