Conductivity is a measure of the ability of water to pass an electrical current.
Knowing the conductivity of the water is important because it measures the amount of dissolved substances, chemicals, and minerals that are present in the water. In general the more contaminants present in the water, the higher the conductivity.
Therefore, the higher the conductivity the more polluted the water is. Temperature can be a big influential factor on the conductivity level in the water.
Read more about the effect of temperature on conductivity in our article The effect of temperature on conductivity