The conductivity of water provides an indication of the quantity of dissolved material present.

Water conductivity measurement is dependant upon a wide variety of inorganic substances or dissolved solids in water solutions. Common dissolved substances are sodium, chloride, sulfates, calcium, bicarbonate, nitrates, phosphates, iron, and magnesium. All of these materials at certain concentrations have the ability to carry an electrical current.

In general, water with high concentrations of dissolved solids is defined as salty while water with low concentrations of dissolved solids is considered as fresh. Salinity is the total of all salts dissolved in water, usually expressed in parts per thousand (ppt).

Water Conductivity (TDS) Measurement

Conductivity or Total dissolved solids (TDS) is defined as the quantity of dissolved material in water, and depends mainly on the solubility of rocks and soils the water contacts. For instance, water that flows through limestone and gypsum dissolves calcium, carbonate, and sulfate, resulting in high levels of total dissolved solids.

A convenient way to measure TDS is to test the conductivity of the sample. Conductivity is a measure of the ability of water to pass an electrical current and is affected by the presence of dissolved solids. As the level of TDS rises, the conductivity will also increase.

Discharges to water can change the conductivity depending on the discharge. A failing sewage system could raise the conductivity because of the presence of chloride, phosphate, and nitrate; an oil spill would lower the conductivity because oil does not conduct electrical current very well.

Conductivity is measured in micromhos per centimeter (mhos/cm) or microsiemens per centimeter (s/cm), equivalent units of measure that can be used interchangeably. Distilled water has conductivity in the range of 0.5 to 3 mhos/cm.

Conductivity increases with decreasing water purity. This fact is useful in numerous industrial, sanitation, purification and control applications, as conductivity measurement provides useful information as to the behaviour or scaling/deposition/foaming tendancies of the water.

Conductivity Meters

Kittiwake provide a full range of conductivity test meters and equipment to assist you in determining the conductivity of your water samples.

The table below gives a chart of recommended tests.
R = Recommended X = Suitable for use

Call us now on +44 1903 731470 to discuss your specific needs, or visit our global network page for offices or dealers near you.