Electrical Conductivity Of Water

What is EC (Electrical Conductivity in water)?

EC or Electrical Conductivity of water is its ability to conduct an electric current. Salts or other chemicals that dissolve in water can break down into positively and negatively charged ions. These free ions in the water conduct electricity, so the water electrical conductivity depends on the concentration of ions. Salinity and total dissolved solids (TDS) are used to calculate the EC of water, which helps to indicate the water’s purity. The purer the water the lower the conductivity. To give a real-life example, distilled water is almost an insulator, but saltwater is a very efficient electrical conductor.

Electric cord with electricity sparkls as symbol of power

 

Major positively charged ions that affect the conductivity of water are sodium, calcium, potassium and magnesium. Major negatively charged ions are chloride, sulfate, carbonate and bicarbonate. Nitrates and phosphates are minor contributors to conductivity, but they are very important biologically. The natural impacts on EC in water are rain, geology and evaporation. Human impacts include road salt, septic/landfill leachate, impervious surface runoff and agricultural runoff.

Aquaread’s EC Testing Equipment

Aquaread manufacture EC water quality testing equipment suitable for portable or fixed applications. The Aquaprobe AP-2000 and the Aquaprobe AP-5000 are efficiently portable, ideal for testing multiple sites quickly and with ease. It’s also suitable for fixed short or medium term monitoring, for example unmanned ground water monitoring in boreholes. The Aquaprobe AP-7000 is specifically designed for long-term use with innovative self-cleaning.

Aquaread’s water conductivity sensor can be used for electrical conductivity monitoring in water, e.g. leave the Aquaprobe AP-7000 in situ to measure EC and other parameters over a long term period. Data is collected in the Aqualogger or with a telemetry device that allows remote data retrieval. It’s also possible to use a portable device such as the AP-2000 to easily take real-time measurements, and track the exact location of the measurements using the Aquameter with GPS.

 

AquaPlus Probe with sleeve on

AP-5000

AquaPlus probe with sleeve off

 

 

 

 

 

Aquaread’s DO and EC meter is combined. It is easy to recognise because it has a screw-on cap and four stainless steel EC sensor contacts on the side. EC is measured on the side of the electrode by the four stainless steel contacts. EC can be measured in the range of 0 – 200 mS/cm or 0 – 200,000 uS/cm and is accurate to +/- 1% of the reading, or +/- 1 uS/cm if greater.

Why use an Aquaread EC Meter for water testing?

An EC meter makes testing and monitoring the electrical conductivity of water simple. EC water conductivity test equipment can be used in the field to take direct measurements of water. The probe that is inserted into the water sample applies a voltage between electrodes. The drop in voltage measures the resistance of water, which is converted to conductivity. Conductivity is reciprocal to resistance and is measured as the amount of conductance over a certain distance. The basic unit is mho/cm, or 1 Siemen, but this does not occur in natural water. EC meters use the units milimhos and micromhos. 1,000,000 milimhos/cm (mS) and 100,000 micromhos/cm (uS) each equal 1 mho/cm.

Ocean waters have water electrical conductivity of about 5 mS, tap water has EC in the range of 50 to 800 uS, depending on the source, freshwater streams may fall in the range of 100 to 2000 uS and distilled water has EC of between 0.5 and 3 uS. EC is relative to temperature. The term “specific conductivity” is used when a value has been corrected to reflect the temperature of the water sample. Aquaread’s water conductivity meter also measures temperature, so gives the value of specific conductivity.

Thermometer measures the temperature of the water

Water conductivity test equipment can be used to build up an understanding of the typical range of conductivity for a particular water body. This can be used as a baseline for regular monitoring and, if there is a significant change in conductivity, this could be an indicator of a discharge or other pollutant entering the water. Conductivity varies with the water source, i.e. ground water, agricultural runoff, municipal wastewater, rainfall. A change in water electrical conductivity can indicate ground water seepage or a sewage leak.

The EC of water has a critical influence on aquatic life. Every kind of organism has a typical range that it can tolerate. In a commercial sense, testing the conductivity of water may be specifically useful for fisheries. Salts and other substances also affect the quality of water for irrigation or drinking, so water conductivity meters can be used when testing the output of water treatment plants.

The water conductivity meter is just one function of Aquaread’s multiparameter water quality monitoring equipment. Use all the parameter readings together to accurately monitor water quality without the need for multiple probes. The EC water testing equipment is suitable for use on surface water, groundwater and wastewater.

Get monitoring with Aquaread

If you would like any more information about water quality monitoring in general please contact us. Click here to see our product range.

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