pH is a measure of the hydrogen ion concentration in water. It is also an indication of acid or alkaline content. The pH scale ranges from 0 to 14, with 7 indicating neutral water. Values less than 7 indicate sharply increasing acidity, and values greater than 7 indicate sharply increasing alkalinity. The pH of water in its natural state varies from 5.5 to 9.0. Determination of the pH value assists in the control of corrosion, the determination of proper chemical dosages, and adequate control of disinfection. The treatment processes used to control corrosivity and scaling involve pH adjustment.