ORP or Redox

ORP is typically measured to determine the oxidizing or reducing potential of a water sample. It indicates possible contamination, especially by industrial wastewater. ORP can be valuable if the user knows that one component of the sample is primarily responsible for the observed value. For example, excess chlorine in wastewater effluent will result in a large positive ORP value and the presence of hydrogen sulfide will result in a large negative ORP value.