Why Measure Water Resistivity?

Water quality analysis

Water quality is vial component of innumerable applications. Unsafe or inadequate water, sanitation and hygiene is the cause of 3.7% of DALYs (disability adjusted life years) worldwide as well as 3.1% of all deaths.

Lack of adequate sanitation is a problem around the world and is one of the most significant sources of water pollution.

Yes, the quality of our drinking water is important, but drinking water is just one application of many; water quality is just as vital for industrial, medical and commercial purposes, as well as lab uses.

Measuring Water Resistivity

Water quality analysis is necessary to ensure the purity of water and to identify problems with sanitation and pollution. Water quality indicators and other methods are used by experts in many fields to determine the purity of water.

One such method includes the measurement of of water resistivity. Water resisitivity is the ability of water to resist an electrical current, which is directly correlated with the amount of dissolved salts in the water. When water has a high concentration of dissolved salts, it will have a low resistivity, and vice versa. Water resistivity measurement can be used to determine the amount of dissolved salt content in water., as well as its ability to resist electrical current.

Water resistivity is measured in Ohms.

Resistivity and Conductivity

Conductivity is the measure of water’s ability to pass an electrical current. Water conductivity is affected by the presence of inorganic dissolved solids, but not organic compounds as they do not conduct electrical current well. Water conductivity is also affected by temperature; the warmer the water, the higher the conductivity. Because of this, conductivity is reported at 25 degrees Celsius.

Ultrapure water does not act a good conductor of electricity. This is evidenced by the 18 megohm-cm resistivity (or 55nS/cm conductivity). Resistivity and Conductivity are inverses of each other. If water has high conductivity, it will have low resistivity, and vice versa. The measurement of resistivity is used for high purity water applications while the measurement of conductivity is employed for the full spectrum of water monitoring.

Water resistivity and conductivity are similar in that they are both affected by temperature. Instruments that measure Resistivity, as well as conductivity, must be compensated to 25 degrees Celsius, as mentioned above.

Monitoring water resistivity and conductivity are just two water quality analysis methods of many.