The electric potential required to transfer electrons from the oxidant to the reductant, used as a qualitative measure of the state of oxidation in water treatment systems. Oxidation-reduction potential (ORP) takes into account the functionality of rivers and lakes for the purposes of dissolving waste materials (dead organisms, pollutants) and cleaning itself. As the ORP increases in value, much of the oxygen remains in the water. For this reason, the bacteria which breaks down tissues and pollutants is capable of working more productively. As a result, the greater value of the ORP means the more progressive the river or lake is.