The conductivity meter measures the electrical conductivity of the water and measures in the result how many solids such as minerals, salts and metals are dissolved in the water. The dissolved substances are expressed in PPM (Parts Per Million). The lower the PPM value, the purer the water. Conversely, the higher the PPM value, the more dissolved solids there are in the water. With watermaker systems, it makes sense to measure the PPM value at regular intervals to check the correct functioning of the device.