What does conductivity measure in water?

Conductivity in water is an important parameter that indicates the ability of the water to conduct an electrical current, which directly correlates with the presence of dissolved ionic substances. When substances such as salts, minerals, and other dissolved solids are present in water, they dissociate into ions, which are charged particles that facilitate electrical conductivity. Therefore, higher conductivity readings typically reflect a greater concentration of these dissolved solids, providing valuable information about the overall quality and composition of the water. This is why measuring conductivity is often used as a quick and effective way to assess water quality, particularly in identifying changes due to pollution or varying environmental conditions.

The other choices do not align with the primary function of conductivity. For example, while temperature can affect conductivity, it does not measure the temperature directly; clarity pertains to the physical appearance and turbidity of water, not its capacity to conduct electricity; and salinity, while related to conductivity (because salinity involves dissolved salts), does not encompass all dissolved solids as conductivity does.