The conductivity of water is the result of ions that carry the electrical current. Ion concentration is frequently reported in parts per million. Because ions carry the electrical current, conductivity is directly related to ion concentration. The higher the ion concentration (expressed in parts per million), the higher the conductivity. For this reason, water bottlers and wastewater treatment facilities like Lenntech use conductivity as a way of measuring the purity of the water they handle. Below is an easy conversion between parts per million and conductivity.
Divide the parts per million value by 0.64 to convert to a conductivity value. Lenntech reports this conversion as a general average value. In practice, different ions have different conductivity. Therefore, to be absolutely accurate, it would necessary to know the concentration of every ion present. This is difficult under most circumstances, so we use an accepted average value instead.
The resulting value is in units of microSiemens per meter. MicroSiemens is a unit of conductivity. Conductivity is affected by the dimensions of the space and the distance the current travels, so it is most often reported in conductivity (Siemens) per unit distance (meters). The SI unit for conductivity is Siemens per meter. You can further convert microSiemens per meter to Siemens per meter by dividing your value by 1,000,000 and changing the units to Siemens per meter.
Convert the value to scientific notation. As conductivity is often either a very large or very small value, reported values are frequently reported in scientific notation. This is accomplished by moving the decimal point until only a one's place is present. The number of places the decimal point was moved to is noted by a base 10 exponent. For example, 6300000.0 is reported as 6.3x10^6 and 0.00043 is reported as 4.3x10^-4.
About the Author
Dr. Alex Tan has been writing in science for more than six years. She is now working as a technical and science writer in California. Tan received her Ph.D. from Johns Hopkins University