ABSTRACT
This chapter deals with important water quality parameters that serve as controlling variables; controlling variables are those that strongly inuence the behavior of many other constituents present in the water. The major controlling variables are pH, alkalinity and acidity, oxidation-reduction potential (ORP),* temperature, and total dissolved solids (TDS). This chapter also discusses several other important parameters that are strongly affected by changes in the controlling variables, such as carbonate, dissolved oxygen (DO), and biochemical oxygen demand (BOD).
