Conductivity

What is Conductivity?
Conductivity is the measure of the water’s ability to conduct an electrical current. It is conducted through water by the dissolved solids in solution. It is a useful indicator to determine if the supply is being contaminated from another source (e.g. an illegal connection). Conductivity is also a good measure of salinity (salt content), which affects the potential dissolved oxygen levels in the water. In addition, it is used as an indicator of how ion-free or impurity-free the sample is; the purer the water, the lower the conductivity. Having said that, totally pure water is insipid and is potentially harmful, so a zero reading of conductivity would not be desirable. Conductivity is measured in micro Siemens per centimeter (?S cm-1), where Siemens is the unit of electric conductance. There is no human health risk associated high with Conductivity. In the Drinking Water Regulations, it is defined as an Indicator Parameter.
What is an exceedance of Conductivity?
The designated limit for Conductivity in the EU drinking water directive is 2500?S/cm. Therefore, any result above this level is an exceedance for Conductivity.
How can an exceedance of Conductivity occur?
Conductivity in freshwater systems is affected by the geology of the area through which the water flows. Streams that run through granite bedrock will have lower conductivity, while those that flow through limestone and clay soils will have higher values. High readings can also come from industrial pollution or run-off from roads. Extended dry periods and low flow conditions also contribute to higher conductivity readings.