What is the Oxidation-Reduction Potential (ORP)?

Oxidation-Reduction Potential Diagram. Drawing explains how an atom loses an electron. Counterpart right shows how an atom gains an electron.

First of all, it’s necessary to understand what ions are.

Ions are molecules with a net electric charge (‘charged molecules)’ that is generated due to the gain or loss of electrons.

Ions are found everywhere – they are in our bodies and in the air around us. Ions are constantly gaining or losing electrons all of the time.

Three main changes to ionized water:

1. pH
2. Oxidation/Reduction Potential (ORP)
3. Molecular Structure

The oxidation-reduction potential (ORP) measures the likelihood of a substance to lose electrons (oxidation) to another substance or gain electrons (reduction) from another substance.

Oxidation-reduction reactions (where both occur at the same time) are known as ‘redox’ reactions (red = reduction and ox = oxidation).

ORP is important in many industries, where the ORP value is an indication of the sanitization potential. For example in the sewage industry, a highly positive ORP value of water is required.

Chlorine is added to swimming pool water as it has a high ORP value which improves its sanitizing properties.

How is ORP measured?

ORP is measured in millivolts (mVs) using an ORP meter. A positive ORP means that the substance is an oxidizing agent and a negative ORP means the substance is a reducing agent. A healthy ORP for the human body is between -150 and -400mV.

What is the oxidation-reduction potential of water?

ORP measures the ability of a chemical substance to reduce (gain electrons from) or oxidizes (lose electrons to) another substance.

The pH (‘potential of hydrogen’) of something indicates the ratio of positively charged hydrogen ions [H+] and negatively charged hydroxyl ions [OH-] present.

Acidic water has a higher concentration of H+ ions and has a pH of less than 7.0. Alkaline water has a higher concentration of OH- ions and has a pH of greater than 7.0 (neutral water has an equal concentration of H+ and OH- therefore its pH is 7.0 'neutral').


How are ORP and pH related?

ORP measures the ability of a chemical substance to reduce (gain electrons from) or oxidizes (lose electrons to) another substance.

The pH (‘potential of hydrogen’) of something indicates the ratio of positively charged hydrogen ions [H+] and negatively charged hydroxyl ions [OH-] present.

Acidic water has a higher concentration of H+ ions and has a pH of less than 7.0.

Alkaline water has a higher concentration of OH- ions and has a pH of greater than 7.0 (neutral water has an equal concentration of H+ and OH- therefore its pH is 7.0 'neutral').

What is the difference between oxidation and reduction?

Oxidation = losing electrons or increase in oxidation state by a molecule, ion or atom, for example when iron goes rusty or a bitten apple going brown when exposes to air (the oxidizing agent in these examples is oxygen).

Oxidation can occur at different speeds; corrosion is an example of slow oxidation and combustion is an example of fast oxidation.

Reduction = gaining electrons or decrease in oxidation state by a molecule, ion or atom, for example how iron is made from iron ore (the reducing agent here is carbon monoxide.

  • An easy way to remember this is ‘OIL RIG’: Oxidation Is Losing (electrons), Reduction Is Gaining (electrons).
  • When oxidation and reduction occur at the same time this is called a ‘redox’ reaction.

There are five main types of redox reactions:

  • combustion (a reaction involving oxygen and an organic fuel such as methane where energy is released)
  • combination (elements combine to create a new compound, for example, hydrogen and oxygen combine to create water)
  • decomposition (the opposite of combination where a substance is broken down into its components)
  • displacement (the replacement of elements with different elements)
  • disproportionation (when a substance is both reduced and oxidized. For example when hydrogen peroxide is poured over a wound)


A rusted car without wheels and windows on the ground, blue sky. Some trees in the background.


What is an oxidant?

‘Oxidant’ is another term for an ‘oxidising agent’ or ‘oxidizer’; a substance that takes electrons from another substance during a redox reaction (the reducing agent accepts these electrons).

Oxidants are used for simple household items such as bleach and combustion reactions, for example in explosives.

The following are all examples of oxidants:

  • Hydrogen peroxide
  • Oxygen
  • Nitric acid
  • Sulfuric acid
  • Ozone is one of the most powerful oxidizing agents known
  • Potassium nitrate (used in fertilizers and gunpowder)
  • Nitrous oxide (laughing gas, used in dentistry)
  • Sodium bismuthate (used in other chemical reactions)
  • Chlorine (antiseptic use in swimming pools and industrially used for textile and paint production)


How can oxidation affect health?

Oxidation is also a natural reaction that occurs within our bodies, for example when the immune system attacks bacteria or the natural aging process.

Free radicals in the body are generally a negative thing, as they oxidize cells, causing damage to the cell membrane and DNA.

Free radicals are unstable and highly reactive molecules that contain an unpaired electron, so are constantly searching for another electron to stabilize themselves.

Low-level oxidative stress is a normal immune reaction while fighting infection. However, if there is an imbalance between the production of free radicals and the body's ability to counteract their damaging effects, this is known as uncontrolled oxidative stress or oxidative damage.

This process accelerates the aging process (causing wrinkles) and underpins a wide range of diseases such as:

  • Hardening of the arteries (atherosclerosis) leading to heart disease and heart attacks
  • Development of cancer
  • Dementia
  • Inflammatory joint conditions
  • Degenerative eye diseases
  • Asthma
  • Diabet

It is thought that encouraging an antioxidant diet (to fight excessive free radicals) could benefit the elderly population.

However, in patients with cancer who are being treated with radiation, this type of treatment creates free radicals that are designed to kill the cancer cells, so antioxidant consumption needs to be avoided, or it could decrease the effectiveness of treatment.


What causes free radicals?
Although free radicals are a natural by-product of energy generation by cells, and cannot be avoided, there are also numerous lifestyle choices and environmental factors that can increase the presence of free radicals in the body:

  • Excessive alcohol consumption
  • Exposure to tobacco smoke (cigarette smoke contains over 4000 toxic chemicals)
  • Chronic stress
  • Exposure to airborne allergens, fungal toxins or pollution
  • Too much exercise
  • Too little exercise
  • Consuming too much-processed food, sugar, calories, refined carbohydrates
  • Eating charbroiled food
  • Sleep deprivation
  • Exposure to occupation chemicals such as radon
  • Exposure to X-Rays
  • Excessive intake of magnesium, iron, copper, or zinc
  • Excessive sunbathing or exposure to ultraviolet light
  • Chronic bacterial, viral or fungal infections such as chlamydia and dental infections
  • Poor liver function

What are antioxidants?

An antioxidant is a substance that inhibits oxidation (‘anti’ = against) and neutralizes free radicals. Antioxidants are widely used in the food industry as preservatives, to prevent the deterioration of stored food items. They are also used in cosmetics and fuel.

Antioxidants naturally occur in whole foods of a plant (fruit/vegetables) and animal origin. Examples of natural-occurring antioxidants include Vitamin A, Vitamin C, Vitamin E, selenium and carotenoids.

Vitamins are also added to food as food additives (for example cereals are often fortified with vitamins). Other foods that are naturally rich in antioxidants (often referred to as ‘superfoods’) include:

  • Fruit, especially berries, grapes, mangoes, and apricots
  • Vegetables such as spinach, kale, leeks, onions, and garlic
  • Dark chocolate
  • Meat products and fish (these are not quite as oxidant rich as the previous items)

Drinks that contain antioxidants include:

  • Red wine (yes, really)
  • Coffee
  • Green tea
  • Fruit or vegetable smoothies

In terms of the ORP value, the more negative the reading, the more antioxidant properties the food or drink has.

For example, orange juice has an ORP reading of -200 to -100mV.

Studies have shown that consuming foods reduces oxidative damage to a far greater extent than consuming supplements.

However, for those people who have a low-nutrient diet or are malnourished, supplements are definitely beneficial

Is alkaline water an antioxidant?

Alkaline water is indeed an antioxidant as it can neutralize free radicals, preventing the damaging effects discussed earlier.

Alkaline water contains numerous active hydrogen molecules that are seeking out free radicals to destroy. Although free radicals are naturally present within the body, a healthy balance of antioxidants is required to prevent DNA and cellular damage from occurring.

Young people can repair this damage easily, but as we age it becomes more difficult, and the damage is irreversible, especially as other diseases and lifestyle/environmental factors can contribute to higher than healthy free radical levels in the body.

Furthermore, the accumulation of all this damage over time is a major contribution to the aging process.

Tap water from the mains supply contains an incredibly high proportion of free radicals.

By drinking alkaline water (with its excess of electrons) you are helping your body fight free radicals and therefore slowing down premature aging.

Even better, alkaline water has another benefit in that it synergistically increases the effects of other antioxidants such as Vitamin C (also important for the absorption of iron, wound healing and maintaining healthy bones and teeth as well as fighting free radicals).

In addition, gut-friendly bacteria are 95% anaerobic (able to exist without free oxygen), meaning they need negative ORP levels to thrive.

This explains why drinking alkaline water improves the digestion of food and increases the absorption of important nutrients by the body.

What does ORP have to do with alkaline water?

The ORP measures the redox state of water, i.e. the ability to reduce (gain electrons) or oxidize (lose electrons) another substance.

Ionizing machines use these principles of chemistry to separate out tap water, generating filtered ionized alkaline water for consumption.

This alkaline water has a negative ORP, meaning better antioxidant properties.


How do water ionizers create alkaline water?

Water ionizers use an electric current (electrodialysis) to redirect and separate tap water into separate alkaline and acidic streams.

The ionizer uses charged plates separated by an ion-permeable membrane which allows the separation of acidic water and alkaline water as well as filtering out of any impurities.

The acidic waste stream is directed to an area for disposal and the ionized alkaline water is available for drinking. Ionized water is best drunk immediately, or can be stored in an airtight container and refrigerated, to prevent denaturing.

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These information were not written by the American Food and Drug Administration, or any other official authority. This site and its products do not promise to diagnose and cure diseases, or protect you from them. Always consult your doctor when you are sick.