The previously developed pattern theory has been applied to background reactions of the solvent and its ions, with water used as the example. Pattern and behaviour equations are developed and discussed, and methods are described for the rapid in situ determination of charge-transfer coefficients and conditional rate constants when a limiting current is known and when it is not, for the reduction of hydrogen ions and water molecules and for the oxidations of hydroxyl ions and water molecules. The voltammetric behaviour of these reactions is rationalised and the determination of coulometric current efficiencies and regulation of conditions to attain the best current efficiency are discussed.