Acidity or alkalinity of water is defined by pH measurement. Generally, pH is measured from 0 to 14 units on a scale. Having pH factor 7 counts neutral, where less than 7 is acidic, and more than 7 is alkaline. If this factor exceeds pH level 8.5, wastewater containing oil will be chemical. If that happens, the water separator will not function properly as a consequence. Thus, to make the tool work appropriately, the pH level needs to be kept down, about 6.8pH.