ORP (Oxidation Reduction Potential), turbidity (measurment of suspended matter), and conductivity (measurment of dissolved salts) are the primary measurements of water quality. ORP is a measure of a water system’s capacity to either release or gain electrons in chemical reactions. Oxidation is a loss of electrons while reduction is a gain of electrons.
ORP control is currently the best available way to achieve and hold a desired level of disinfection.
Ozone, peroxide, hypobromite, and hypochlorite are examples of strong oxidizers that are used in water quality. Maintaining a high oxidation level, combined with filtration is primary method of sanitation in virtually all municipal water supplies and swimming pools. Alternative methods of sanitizing water are reverse osmosis filtration, distillation, and heating. Microrganism kill rate in water is strongly related to ORP, independent of the particular type of oxidizing chemical selected. In fact, if the millivolt level is held, the kill will occur regardless of the significant variables like pH, conductivity, temperature, complexing ions or other organics. For swimming pools at a pH between 7.2 and 7.6, the ORP value must be kept above 700 mV to kill unwanted organisms.