Answering Questions About ORP

I have been asked many times over, “What is ORP?” and “Why is it important for hydrogen-rich water?” Well, for starters, ORP stands for Oxidation Reduction Potential. ORP values or meters are widely used in the hydrogen water industry in relation to ionized water or ionized water demonstrations. In light of the confusion surrounding ORP, I have decided to gather a few of my top responses regarding ORP and list them in this article. These writings of mine should help clear up the confusion and provide some objective facts about ORP and its importance or lack thereof when considering hydrogen-rich water.

Question: Can you talk about the ORP value of water and where that ORP value comes from?  I’ve had a high negative value ORP while having very little H2 present.  I used to think the high negative ORP value was due to the H2 concentration/presence, but apparently, that may not be the case.

T.H. Response: ORP values are based on the Nernst equation, which was developed by Walther Nernst, a German chemist in the late 1800s early 1900s. ORP measures the comparison of the relative concentrations of REDOX couples (chemical species) within a solution, such as the chemical element chlorine (Cl₂, oxidative state) vs chloride (Cl^–, reductive state). For instance, in ionized water (e.g. a form of hydrogen water), the redox couple that is being measured is H₂ (weak reducing agent) and H⁺ (protons, which dictates pH, also strong oxidizing agent). The Nernst equation represents this measurement in an electrical/voltage potential. This leads to the prominent misconception that water can hold a positive or negative charge. This misconception is false due to the principle of electroneutrality, which states that water is prevented from having a charge because positive and negative ions must balance, resulting in water being neutral in its charge.  

Source: Electroneutrality

Here is the actual Nernst equation for H₂ and H⁺ (ionized water) so you can see what it looks like: 

Emv = E°- (RT/zF) log [H₂/H⁺], where E0 represents a reference voltage.

If you bubble hydrogen gas into the water the ORP becomes negative as H₂ is responsible for the negative ORP reading. This was demonstrated in an article on hydrogen water.

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Now, the reason why you can have such a high negative ORP reading with low dissolved levels of H₂ (undetectable) is that the pH of the water has a far greater influence on the ORP reading/meter than H₂. H₂ is responsible for making the meter go negative as it is the reducing agent. However, since there is a huge void in H⁺ (protons or acid) with alkaline water, the more you increase the pH,  the more the meter will go negative. Virtually, you can have a 0.1 mg/L (ppm) dissolved H₂ reading within 11.0 + pH water, and have a high ORP reading (-500 ~ -700+). The other scenario is you can have a 3.0 mg/L (ppm) measurement of dissolved H₂ in water measuring 7 pH and have a low ORP reading (-100 ~ -200). For this reason, I tell people that ORP meters can detect the presence of H₂ but cannot accurately measure the dissolved H₂ concentration (mg/L or ppm) in your water.  ORP values are an irrelevant reading and tool when trying to measure or assess your H₂ mg/L (ppm) reading. Keep in mind all that is stated above only pertains to hydrogen water /ionized water. Other redox couples influence the meter differently since they are not tied to the pH of water such as the REDOX couple H₂/H⁺. Also,  the water does not act as an antioxidant but H₂ acts or exhibits antioxidant-like effects. I would advise you to invest in H₂Blue drops which can accurately measure the H₂ concentration in your water.

Sources: 

Question: “If H₂ does not affect liquid’s pH, like you said in the video, so what makes the water become alkaline after being processed by the machine?”

T.H. Response: The reason the water changes in its pH during electrolysis (ionization) is due to the fact that H⁺ ions (protons or the acid component of water) are being reduced (gaining electrons) to form hydrogen gas (H₂). Secondly, water ionizers electrolytic cells contains Teflon ionic membranes, which are semi-permeable and only allows electrons to flow. These membranes keep the cathode (electrode) and the anode (electrode) separate, producing an alkaline pH at the catholyte and an acidic pH at the anolyte. This is where the term ERW (Electrolyzed Reduced Water) comes from. You’re literally reducing the acid (H⁺ ions) in the water to form hydrogen gas (H₂). So in essence, water ionizers produce hydrogen gas at the cathode (negative side of the electrolytic water cell or where alkaline water is produced) and as a by-product, the pH of the water will increase. This is standard for all standard or newer generation water ionizers. 

Question: “Can other things produce a negative ORP and can a negative be dangerous at times?”

T.H. Response: There are many different beneficial agents that can produce a negative ORP, such as Vit C, polyphenol antioxidants, catechins, flavonoids, carotenoids, etc, etc. As for the agents that can produce a negative ORP and may be damaging or dangerous to the human body, there are numerous or plenty of these as well, such as borohydrides (e.g. LiBH4, KBH4, NaBH3CN), reductive sulfites, hydrazines, derivatives of hydrazines, dihydropyridines, dihydro-furan derivatives, combinations of dihydro-trigonelline also some forms of aluminum. However, the main takeaway is, ORP (primarily pertaining to ionized and/or hydrogen water) is only an indicator that a reducer or oxidant is present. It neither tells you what that agent is or how much is actually dissolved into the water, both of which are VERY important to know. When it comes to hydrogen-rich water there is a better tool to use to answer these questions.

Question: Is ORP how you measure hydrogen-rich water?

T.H. Response: ORP readings are flawed and incapable of accurately measuring dissolved H₂ in water (not a useful tool for measuring the therapeutic capacity of H₂ water). However, it can detect the presence of dissolved hydrogen gas in the water. 

For example, hydrogen is responsible for the ORP meter going negative, nevertheless, it only takes 1 x 10-5 mg/L (0.00001 mg/L (ppm)), or one hundred-thousandth of a milligram per liter of H₂ to produce a negative ORP of -260 mV. 

This is considering there are no other REDOX couples the meter is measuring. This infinitesimal amount of hydrogen gas (needed to produce a negative ORP reading) is nowhere near what’s deemed therapeutic for human consumption, which is 0.5~1.6+ mg/L (ppm). This is one of the reasons alkaline ionized water can produce a high negative ORP reading but can have undetectable dissolved hydrogen concentrations. The other main reason is that ORP is highly, better yet, extremely influenced by pH according to the Nernst equation for the reduction potential of ionized water, (E = E0-RT/zF*Log[H₂/H⁺]). You can see the primary REDOX couple for ionized water is (H⁺/H₂). H⁺ (hydrogen ions or protons) dictate the pH of water or a solution. This is why ionized water’s ORP can be so high (-500~-800) because the pH of the water is so high (above 10 pH). There are far more H⁺ ions in the water than H₂ molecules, meaning a 1 unit change in pH will significantly change the ORP reading. This is why pH has a FAR GREATER INFLUENCE on the ORP reading than H₂ ever will. I know this all can be confusing so here is the summary and takeaways. 

1. ORP meters can detect the presence of dissolved hydrogen but cannot accurately measure it.
2. It takes an infinitesimal amount of dissolved hydrogen gas to prompt the ORP meter to go negative. 
3. Alkaline water made by other means (NaOH, sodium hydroxide) will still have a positive reading. Only alkaline water made by an ionizer has a negative ORP reading due to the dissolved H₂.
4. pH has FAR GREATER INFLUENCE on ORP readings than dissolved hydrogen gas due to the H⁺ ion concentration (which dictates pH). Another reason why ORP readings can’t be trusted.
5. The best way to accurately measure dissolved hydrogen is to measure it directly by gas chromatography or titration (H₂Blue), which is a cheap, easy, and convenient method. H2Blue only works on water.

What I mentioned above is only the tip of the iceberg and simplified. I’ll attach a more in-depth scientific breakdown of ORP written by a colleague of mine. If you’re interested in the read, it will give you a more in-depth and better understanding of the topic. Also, I created an H₂Minutes video on this topic that will help you understand the topic as well.

Scientific ORP pdf: https://www.h2sciencesinc.com/orp.htmld