EM Line Locating · Non-metallic pipes · drains
Sonde Drain & Duct Tracing by EM.
Push a sonde — a small battery transmitter — through a non-metallic pipe, drain, or duct, and trace it from the surface as if it were a metal line. The EM answer for plastic, clay, and concrete lines that carry no signal of their own.
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Best suited for
Why it's used
- Locates lines EM signal can't travel along
- Pinpoints a sonde's exact position and depth
- Follows a CCTV camera head to mark a defect from above
- Turns 'non-locatable' plastic into a marked route
How it works
- 1
Insert the sonde
A sonde is attached to a push rod, drain camera, or duct rodder and fed into the line. It transmits a locating frequency from wherever it sits — a travelling point source inside the otherwise invisible pipe.
- 2
Locate the point
The receiver pinpoints the sonde's position and depth from the surface. Advancing the sonde and re-locating at intervals traces the whole line, bend by bend, even through plastic and clay.
- 3
Mark defects live
Paired with a CCTV inspection, the sonde rides the camera head — so when the camera finds a blockage, crack, or connection, its exact ground position and depth are marked from above on the spot.
- 4
Integrate the picture
Sonde traces combine with EM line locates and GPR imaging into one marked, depth-noted picture of conductive and non-conductive lines together — the complete subsurface map a dig actually needs.
Frequently asked
How do you locate a plastic pipe that carries no signal?
You give it one. A sonde — a small self-powered transmitter — is pushed through the pipe on a rod or camera, and because it broadcasts its own locating frequency, the receiver can pinpoint it from the surface exactly as if the pipe were metal. Advancing it through the line and re-locating traces the whole route. It's the standard EM answer for plastic, clay, and concrete lines.
Can you locate exactly where a sewer is blocked or broken?
Yes — that's one of the sonde's best uses. Run a CCTV camera with a sonde in its head: when the camera reaches the blockage, root intrusion, or crack, you locate the sonde from the surface and mark the precise spot and depth. The repair crew digs one hole on the defect instead of excavating the whole line searching for it.
What's the difference between a sonde and a tracer wire?
A sonde is a moving point source you push through the pipe to trace it once; a tracer wire is a conductor buried alongside a non-metallic line at installation so the line can be actively located any time later. Sonde tracing finds existing plastic lines on demand; tracer wire is how new plastic mains are made permanently locatable. We use sonde tracing for existing lines and recommend tracer wire on every new non-metallic install.
Does sonde tracing work at any depth?
Within the sonde's range, which depends on the sonde's size and frequency and the soil — larger sondes reach deeper, and the same conductive clays that attenuate GPR also shorten sonde range somewhat. For typical residential and commercial drain depths it's reliable; for deep municipal lines a higher-power sonde is selected. We match the sonde to the line, and confirm depth at each located point.
Related EM methods
Active EM Line Locating
Apply a known frequency to a target line and trace only that line — the precise, unambiguous core of electromagnetic locating. Direct connection or signal clamp puts a traceable signal on a specific conductive utility so it stands out from everything else in the ground.
ViewTracer Wire Locating & Installation
Locate plastic mains through their tracer wire — and where there isn't one, advise on installing it. The permanent way to keep non-conductive water, gas, and irrigation lines findable for the life of the asset.
ViewEM + GPR Utility Clearance Survey
The complete pre-dig clearance: passive sweep, active EM tracing of every conductive line, GPR imaging for non-conductive lines and confirmation, sonde tracing for drains, and depths at the dig point. The single survey that makes breaking ground safe — and the everyday private locate done right.
ViewCable & Sheath Fault Locating
Pinpoint where a buried cable or tracer wire has failed — a sheath fault, break, or short — so the repair is one targeted excavation instead of a guessed trench. EM fault-finding for the lines that have stopped doing their job.
View← EM line locating hub·For contractors & pros·Utility locating applications·GPR services
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