Conductivity sensors measure the ability of a solution to conduct an electric current. This ability is determined by the amount of ions contained in the solution, and the amount of ions is one of the parameters used to determine the amount of impurities in a liquid.
Measuring electrical conductivity is a fairly simple and at the same time effective way to control water quality - purified water, tap water, NaCl solutions and sea water of the same temperature have different electrical conductivity.
