You can't reduce water losses you don't measure. Before a utility can find leaks, set up district metered areas (DMAs) or bill a large consumer fairly, it needs reliable bulk flow meters on its trunk mains and zone inlets. Three technologies dominate: electromagnetic, ultrasonic and Woltmann (mechanical turbine). This guide compares them for utilities, design consultants and contractors.
How each technology works
- Electromagnetic ("mag") meter: water moving through a magnetic field induces a voltage proportional to velocity. No moving parts, full-bore and no pressure loss. It needs electrically conductive liquid, which water is.
- Ultrasonic meter: sound pulses are sent with and against the flow, and the difference in transit time gives velocity. No moving parts. Available as inline spool or clamp-on.
- Woltmann meter: a helical turbine turns with the flow and drives a mechanical or electronic register. Simple and economical, but it has moving parts that wear.
Comparison table
| Criterion | Electromagnetic | Ultrasonic (inline) | Woltmann |
|---|---|---|---|
| Typical sizes | DN 15 – DN 2000+ | DN 15 – DN 600 (inline); any size clamp-on | DN 40 – DN 500 |
| Low-flow accuracy | Excellent | Excellent | Moderate |
| Moving parts | None | None | Yes (wear over time) |
| Pressure loss | None | None/very low | Low–moderate |
| Power | Mains or long-life battery | Battery (10–15 yrs typical) | None for mechanical register |
| Sensitivity to dirty water | Low | Low–moderate | Debris can damage the turbine |
| Straight pipe needed | ~5D up / 2D down (often less) | ~5–10D up / 3D down | ~3–10D up depending on model |
| Price | Higher | Medium–high | Lowest |
| Best for | Trunk mains, pump stations, DMA inlets, large sizes | DMA, commercial bulk, battery sites | Irrigation, simple bulk billing, budget projects |
Standards to reference: ISO 4064 / OIML R49 for water-meter metrology and MID approval where required.
Installation essentials
- Full pipe: the meter must always run full. Avoid high points, and install upstream of a control valve where possible.
- Straight runs according to the manufacturer's data. Avoid placing a pump, elbow or partly-open valve directly upstream.
- Isolation: gate valves on both sides, plus a dismantling joint so the meter can be removed for verification.
- Air: fit an air valve at the nearest high point. Trapped air is a common cause of meter error.
- Chamber: a drained, accessible chamber with a cover of the correct EN 124 class.
- Grounding: electromagnetic meters need correct earthing rings or electrodes, especially on PE pipelines.
Telemetry: from meter to platform
Modern bulk meters provide pulse, Modbus, 4–20 mA or built-in GSM/LTE/NB-IoT outputs. These feed SCADA or a state monitoring platform, so the utility can see night flows and spot leaks in hours instead of months.
What to write in the BOQ
*"Electromagnetic flow meter DN 300, PN 16, flanged EN 1092-1, accuracy class per ISO 4064 / OIML R49, battery-powered with GSM/NB-IoT data logger, IP68 sensor, installed with upstream/downstream gate valves, dismantling joint and earthing rings, in drained chamber with D400 cover."*
Quick selector
- Trunk main DN 600–1000 → electromagnetic, mains or battery powered with telemetry.
- DMA inlet DN 150–300, no power on site → battery electromagnetic or inline ultrasonic.
- Irrigation or farm bulk metering → Woltmann with a pulse output.
- Temporary leak survey → clamp-on ultrasonic.
GON project experience
GON equipped Tbilisi's central trunk water mains with metering devices and connected them to state platforms. We also supplied flow meters for water-supply construction and rehabilitation projects in Kartli, Kakheti, Kvemo Kartli, Mtskheta-Mtianeti, Imereti, Racha, Svaneti and Samtskhe-Javakheti, including the Urban Services Improvement Programme, Tranche 5.
Related products: Water metering · Gate valve · Dismantling joint · Manholes & covers
Further reading: Remote-read water meters: what to specify
Need help sizing a meter?
Send the flow range (min/max), pipe size and pressure to sales@gon.ge, or call +995 595 818 800.
GON supplies drainage, water, gas and road-infrastructure products to contractors, utilities and IFI-funded programmes across Georgia.