Measurements · Water Quality
Conductivity
Also known as EC, electrical conductivity, actual conductivity
Electrical conductivity of water (ion content).
What it is
What is conductivity?
Conductivity is a measure of how readily water conducts an electric current, reported in microsiemens per centimeter. It reflects the total concentration of dissolved ions (salts, acids, and bases) in the water. Pure water is a poor conductor; every dissolved ion, from sodium and chloride to calcium and nitrate, adds to its ability to carry current, so conductivity is effectively a proxy for the total dissolved ionic content. It does not identify which ions are present, but it responds instantly to any change in them, which makes it one of the most useful and dependable general-purpose indicators in water monitoring. Conductivity underpins several derived parameters: corrected to a reference temperature it becomes specific conductance, and from that the sonde estimates salinity and total dissolved solids.
Because it is stable, cheap to measure, and quick to react, conductivity is logged in almost every water-quality program as a baseline and an early-warning channel.
Health and operational effects
A stable conductivity is the signature of a healthy, consistent water source; a sudden change signals that something has entered the water. A spike can mean a saline intrusion, a road-salt runoff event, an industrial or sewage discharge, or a fertilizer-laden inflow, while a drop can mark dilution by rainfall or a change in source. In freshwater ecosystems, both very high and rapidly changing conductivity stress organisms adapted to a narrow range.
How it is measured
How Conductivity Is Measured
Conductivity is measured by applying an alternating voltage across electrodes, or by inducing a current in the water without contact, and reading the resulting current: the more ions, the higher the conductance. It is one channel of a multiparameter sonde connected to a Thiamis gateway. Because conductivity rises steeply with temperature, the sensor always logs temperature alongside it so the reading can be normalized to specific conductance. Conductivity cells are relatively rugged, but fouling (and, in contacting cells, deposits on the electrodes) changes the cell geometry and causes drift. Periodic cleaning and calibration against a standard solution are essential.
An instrument on Thiamis5
A third-party instrument connected to a Thiamis gateway, reporting into the same Environet account.
Placing conductivity sensors
Conductivity is measured in-situ by the sonde at a representative point: mid-channel in a river, near an intake, or at an outfall for discharge monitoring. Because it reacts instantly to any ionic change, it is one of the best channels for continuous logging and alarms: a step change in conductivity is often the first evidence of a spill, an intrusion, or a runoff event, ahead of slower parameters. Siting the sensor where the water is well mixed avoids misleading readings, and regular cleaning and calibration keep the cell constant true over the deployment.
Every device and option that measures Conductivity 5
| Device / option | Type | Base platform | Measures |
|---|---|---|---|
 Van Essen Instruments · Mini-Diver, Cera-Diver, Micro-Diver… | Water Level & Flow | Thiamis | |
 YSI · EXO1, EXO1S, EXO2… | Water Quality Sondes | Thiamis | |
 In-Situ · Level TROLL 300, Level TROLL 400, Level TROLL 500… | Water Quality Sondes | Thiamis | |
 Spectra Scientific · Spectra Litmus 6, Spectra Litmus 4 | Water Quality Sondes | Thiamis | |
 YSI · 6600 V2, 6600EDS V2, 6920 V2… | Water Quality Sondes | Thiamis |
Where it is monitored
Solutions That Monitor Conductivity
Each one links to the solution page showing what that industry measures it for.
Water Quality Monitoring
Core parameterConductivity is a fast, reliable proxy for the total dissolved-ion content of water and one of the most useful early-warning parameters in a monitoring program: a sudden change flags a pollution event, a saline intrusion, or a discharge.
Aquaculture & Fish Farming
Often addedDissolved oxygen, temperature, and ammonia control
Article Library
Reading on Conductivity
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Related
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Questions
Conductivity FAQ
What does conductivity measure?
Conductivity measures how well water carries an electric current, which depends on the total concentration of dissolved ions such as salts. It is a proxy for dissolved ionic content: the more dissolved salts, the higher the conductivity. It does not identify individual ions but responds instantly to any change in them.
Why does conductivity change suddenly?
A sharp change usually means something has entered or altered the water: a saline intrusion, road-salt runoff, an industrial or sewage discharge, or dilution by heavy rain. Because conductivity reacts instantly, a step change is often the earliest sign of a pollution or intrusion event, which is why it is a favorite alarm channel.
How are salinity and TDS related to conductivity?
Both are derived from conductivity. After correcting the raw reading to a reference temperature to give specific conductance, standard relationships estimate salinity and total dissolved solids from it. This is why a single conductivity sensor can report all three related values.
How do I monitor conductivity?
Deploy a multiparameter sonde with a conductivity cell connected to a Thiamis gateway, logging continuously with alarms on sudden changes and regular cleaning and calibration. Use the configurator to pair a logger with a sonde covering conductivity alongside specific conductance, salinity, temperature, and pH.
Monitor Conductivity on the Record
Schedule a callConfigure Conductivity Monitoring All parameters
A 30-minute call: you tell us about your application, then we demo the solution for it.