How a Geoelectric Water Detector Works
The OKM GeoSeeker and GeoSeeker Mini use a geoelectric measurement based on the Schlumberger method. Electrodes are set in the ground along a line; two inject current and two measure the voltage drop, and the instrument calculates the apparent resistivity of the ground at each scan point. OKM explains the reading this way: water and water-bearing gravel conduct electricity well and show low resistance, while cavities conduct poorly and show high resistance. Each scan point takes at least 16 seconds to measure on both models.
Because the method reads resistivity, neither GeoSeeker finds coins, relics, gold or any other metal object. If metal is your target, see the OKM 3D ground scanners in the OKM Fusion series and OKM Rover series, or a conventional metal detector.
OKM GeoSeeker: Deeper Surveys with 3D Results
The OKM GeoSeeker is the larger system. OKM rates it to 250 m (820 ft); in Active Scan you set a start and end depth anywhere between 5 m (16 ft) and 250 m (820 ft). It has three scan modes:
Active Scan (Accurate): injects current through two electrodes and measures with two more, for water deposits, caves and impervious layers.
Active Scan (Quick): a faster version of the same current-injection measurement.
Passive Scan: reads the ground's natural voltage with two electrodes, without injecting current, and OKM says it detects flowing underground water only.
The GeoSeeker is run from an Android tablet that connects to the controller over Wi-Fi. Results appear in 3D on the tablet, with water and water-bearing gravel shown in blue and cavities or impervious layers in reddish colors, and can be analyzed further in the included Visualizer 3D Studio Professional Edition. A pre-configured Windows notebook is an OKM option, not included.
The GeoSeeker kit is a two-unit system: a controller that OKM rates for at least 16 hours on charged batteries, and a power box that sends the current, weighing 15.8 kg (about 35 lb) on its own and running about 100 hours at minimum power, 40 hours at average power and 8 hours at maximum. As of October 2026, OKM lists four electrodes, two 255 m voltage cable drums, two 26 m power cable drums, two 2 m connecting cables, eight rechargeable AA batteries and a protector case in the delivery scope.
OKM GeoSeeker Mini: Simpler Setup to 100 m
The OKM GeoSeeker Mini is a single control unit with a 3.5 inch color touchscreen and no tablet. OKM rates it to 100 m (328 ft). You choose the measurement depth and the number of scan points, then follow the on-screen pictures, which use icons rather than text. The electrodes are moved several times during one measurement, results show after each scan, and the final result is a 2D image. OKM rates the operating time at about 6 to 8 hours.
As of October 2026, OKM lists the GeoSeeker Mini kit as the control unit (about 4.5 kg), four electrodes, two power cable drums with 100 m of cable each, two 10 m voltage cables, two 2 m connecting cables, a power pack, a charger, a travel adapter set and a protector case. OKM notes delivery scope can change for both models; each product listing carries what we supply.
Which GeoSeeker for Which Job
Pick the GeoSeeker Mini when your target depth is within 100 m, you want a self-contained unit one person can learn quickly, and a 2D result is enough to decide where to drill or dig. That covers many shallow well and cavity questions, and it is the simpler and lower-cost of the two.
Pick the GeoSeeker when you need to survey deeper than 100 m, set a precise depth window, look specifically for flowing water with Passive Scan, or want 3D results and the Professional Edition software for reports. It is a heavier kit with long cable runs, so plan on space to lay out the line.
Both are survey instruments that give a resistivity picture of the ground, not a guarantee of water. We suggest customers treat a GeoSeeker result as the reason to drill in one spot rather than another, and to read the depth figures, which are OKM's ratings, as the maximum each system is built to measure.
Cavity Searches: GeoSeeker or Radar
A GeoSeeker reads a cavity as a high-resistance zone. Some cavity searchers would rather see the structure itself as an echo-based image; that is what the OKM Gepard GPR ground-penetrating radar records. For voids behind walls, the thermal probe on the OKM Delta Ranger is built for that.
