Oxidation reduction potential (ORP)
Oxidation reduction potential also known as Redox potential is a parameter which measures the quality of water. It indicates the capability of the substance to reduce or oxidize another substance. In other words, ORP determines the degree to which extent a given solution is capable of either accept or release electrons through chemical reactions. ORP is measured by the help of ORP meter which has a range of -2000 to +2000 units expressed in terms of volts (V) or millivolts (mV).
ORP sensor works by measuring the amount of dissolved oxygen.
- The positive (+) ORP reading means the solution is an oxidizing agent. The more positive ORP, the more oxidize the solution is, that means the solution has a higher ability to destroy harmful contaminants. For example: if any given solution indicates ORP as (+) 200mV, then this solution is 2 times more oxidize than the solution indicates ORP as (+) 100mV.
- The negative (+) ORP reading means the solution is a reducing agent. The more negative ORP reading, more anti-oxidizing the solution is, that means the solution contains less dissolved oxygen as the organics are consuming the oxygen. For example, the solution with ORP (-) 200mV is 2 times more anti-oxidizing than a solution with ORP (-) 100mV.
Except ‘alkaline ionized’ water, most other types of water are an oxidizing agent (ORP value is positive). Alkaline ionized water has negative ORP value, indicates it as an anti-oxidizing agent, and it has the ability to release its extra electrons that help to destroy the toxicity of free radicals.
Potential hydrogen (pH)
pH value indicates the hydrogen concentration which determines the nature of the solution, whether the solution is alkaline or acidic or neutral. It is measured by the pH scale, and its index value is related to the ratio of positive hydrogen ions (H+) and negative hydroxyl ions (OH-).
- The solution is called neutral (i.e. pH value = 7), when the concentration of OH- and H+ ions are equal.
- The solution is called acidic (i.e. pH value <7), when the solution of H+ ions is higher than OH- ions.
- The solution is called alkaline (i.e. pH value >7), if the concentration of OH- ions are higher than H+ ions.
The pH value is indicated in logarithmic scale. Hence, when the pH value increases or decreases by 1unit, it means the concentration of hydrogen ions changes by 10 times. Ex: solution with pH value 4 is ten times more acidic than a solution with pH value 5.
Importance of ORP and pH
Higher positive ORP is desirable for swimming pools, spas, and sewage water as more oxidation will happen which will destroy all the pathogens, and contaminants. Normally chlorine is added to drinking water as it has high ORP and will oxidize and destroy all the harmful micro-organisms.
Water with pH value 6.5 to 8.5 is considered as safe for drinking, as this value indicates that the water is neither acidic nor alkaline enough to be harmful to human body. When pH value drops to below 6.5 and also rises above 8.5, water becomes toxic, causes various health issues like eye and skin irritation, diarrhea, nausea, gastrointestinal upset, etc.