Most hydrogen water shoppers see "1.6 PPM" on a machine's spec sheet and assume higher is better. Some see "–800 mV ORP" and assume that means more hydrogen. Most of the time, neither assumption holds up.
The three numbers that appear most often in hydrogen water marketing — PPM, PPB, and ORP — measure fundamentally different things. Two of them reflect hydrogen concentration directly. One of them, ORP, does not. Knowing the difference is the single most important thing a buyer can understand before evaluating any machine's claims.
This article explains what each metric means, where each one comes from, and how to use them to actually assess what a machine produces. If you've already read our overview of what hydrogen water is and how it's made, this goes deeper on the measurement side.
What Does PPM Mean in Hydrogen Water?
PPM as a Measurement of Mass per Volume
PPM stands for parts per million. In the context of dissolved substances in water, it expresses milligrams of a substance per liter of liquid (mg/L). When a hydrogen water machine claims to produce "1.6 PPM," that means it is dissolving approximately 1.6 milligrams of molecular hydrogen (H₂) into every liter of water it produces.
The unit is a weight-to-volume expression. One PPM of dissolved hydrogen equals one gram of hydrogen per one million grams of water — or, more practically, one milligram per liter. Because molecular hydrogen (H₂) is the lightest molecule in existence, even a small mass represents an enormous number of molecules relative to other dissolved substances. Measures dissolved molecular hydrogen concentration in mg/L, and PPM is the unit of choice in virtually all published clinical research on hydrogen water.
When you read a spec sheet or study abstract citing a concentration of 0.8 mg/L, 1.3 mg/L, or 1.6 mg/L, those numbers are PPM values. The unit and the metric are interchangeable in this context.
PPM and the Research Threshold Question
Published clinical research has used hydrogen water across a wide range of concentrations. As of April 2026, PubMed lists over 2,000 peer-reviewed papers on molecular hydrogen across various delivery methods. The concentrations used in human studies range from below 0.3 PPM to above 7 PPM. A frequently cited reference point is 0.5 PPM — not because any regulatory body established it as a threshold, but because many review papers observe that trials reporting measurable effects generally used water at or above this level.
Nakao et al. (2010), in a pilot study published in the Journal of Clinical Biochemistry and Nutrition, used hydrogen-rich water at approximately 1.1–1.3 mg/L and examined its effect on oxidative stress markers in 20 subjects with potential metabolic syndrome over eight weeks. Researchers reported reductions in urinary TBARS and increases in SOD activity (PMID 20216947). The study was an open-label pilot — not a blinded trial — and the authors described the findings as preliminary.
No regulatory body has established an official effective dose for molecular hydrogen in water. What PPM provides is a framework for comparing machine output to concentrations used in published research.
What Is PPB — and Why Do Some Products Use It?
Converting Between PPM and PPB
PPB stands for parts per billion. In water measurement, it expresses micrograms of a substance per liter (µg/L). The conversion is simple: 1 PPM equals 1,000 PPB. Hydrogen water means parts per billion when marketed with the PPB unit — a machine advertising "1,600 PPB of dissolved hydrogen" is claiming the same output as one that says "1.6 PPM." They are identical measurements expressed in different scales.
Research papers most commonly report dissolved hydrogen in mg/L, which is equivalent to PPM. Consumer-facing marketing sometimes uses PPB, either because it matches the output range of a specific device or because larger numbers appear more favorably in comparisons. Neither unit is inherently misleading — as long as it is clearly labeled and not compared across units without conversion.
Why Brands Sometimes Choose One Over the Other
There is no agreed industry standard for which unit to use in consumer marketing. PPB levels look larger on paper: 800 PPB appears more impressive than 0.8 PPM, even though they express the same concentration. The confusion compounds when a brand advertises "1,600 PPB" alongside a competitor's "1.6 PPM" without clarifying the equivalence.
Practically speaking: always convert to the same unit before comparing. If a spec sheet uses PPB and a research paper uses mg/L, divide the PPB value by 1,000 to get the PPM equivalent. That step alone eliminates most of the apparent complexity in reading hydrogen water claims.
What ORP Measures
The Definition of Oxidation-Reduction Potential
ORP stands for oxidation-reduction potential, also called redox potential. It measures the tendency of a solution to acquire or release electrons, expressed in millivolts (mV). A positive ORP indicates an oxidizing environment — one that tends to remove electrons from other compounds. A negative ORP indicates a reducing environment — one that tends to donate electrons.
ORP meters measure this electrical potential through a probe placed in the water sample. They are standard tools in water quality monitoring, food safety, pool management, and industrial chemistry. In those applications, the ORP reading provides useful, actionable information about a solution's chemical behavior. The question is whether that same reading is useful for evaluating dissolved hydrogen concentration in drinking water.
Negative ORP and What It Signals
When molecular hydrogen dissolves in water, it shifts the solution toward a more negative ORP reading. This led to a widespread assumption in early hydrogen water marketing: more negative ORP means more dissolved hydrogen. Readings like –200 mV, –400 mV, or –800 mV were presented as proxies for hydrogen concentration, and an orp meter became a common consumer verification tool.
The problem is that ORP cannot isolate hydrogen's contribution from other variables. The redox potential of water is influenced by pH, temperature, and dissolved mineral content — all of which can produce strongly negative ORP readings regardless of how much hydrogen is actually present. The orp readings on a spec sheet may reflect the machine's water chemistry as much as its hydrogen output.
Why ORP Cannot Reliably Tell You How Much Hydrogen Is in Your Water
The pH Problem
In 2022, researchers published a peer-reviewed analysis in Frontiers in Food Science and Technology specifically examining whether ORP could serve as a reliable measure of dissolved hydrogen concentration. The paper's conclusion was unambiguous: ORP and ORP-based H₂ meters are not recommended for testing or comparing the concentration of H₂ in water (Frontiers in Food Science and Technology, doi: 10.3389/frfst.2022.1007001).
One central finding: because pH plays such a large role in ORP readings, a one-unit increase in pH — from pH 7 to pH 8, for example — influences the ORP by an amount equivalent to increasing the H₂ concentration by a factor of 100. In plain terms: a glass of alkaline water at pH 9 can register –800 mV ORP while containing less dissolved hydrogen than a neutral-pH glass registering –300 mV. The more negative orp reading is reflecting pH, not hydrogen.
The Temperature Problem
The same 2022 analysis found that temperature compounds the problem. At a saturated hydrogen concentration and pH 7, a 20°C temperature change alters the ORP reading by approximately 30 mV — an amount that corresponds to changing the actual hydrogen concentration by a factor of 10. Water that has cooled between production and testing will register differently on an ORP meter than the same water tested immediately after production, even if its actual hydrogen content is identical.
This temperature sensitivity creates a measurement that shifts based on how and when you test it, not just on what's in the water. For a machine that needs to demonstrate consistent output over time, an ORP meter cannot distinguish a real change in hydrogen production from a routine fluctuation in water temperature.
What the 2022 Peer-Reviewed Analysis Found
The Frontiers analysis modeled the mathematical relationship between ORP, pH, temperature, and dissolved hydrogen. Its finding: the magnitude of a negative orp reading provides no useful estimate of the level of hydrogen in water. Two samples with identical hydrogen concentrations can produce dramatically different ORP readings depending on their pH and temperature. Two samples with identical ORP readings can contain vastly different amounts of dissolved hydrogen.
The practical implication for anyone evaluating machines: if a product's marketing is built primarily around ORP figures, that is a signal about what the manufacturer chose to measure — and what they chose not to. The number that matters is dissolved molecular hydrogen, measured directly.
The Right Way to Measure Dissolved Hydrogen
Gas Chromatography: The Laboratory Standard
Gas chromatography (GC) is the recognized reference method for measuring dissolved hydrogen in water. A water sample is injected into a heated port; the hydrogen volatilizes, passes through a separation column, and is quantified by a thermal conductivity detector against a calibration standard. It is not influenced by pH, temperature, or mineral composition. When research labs verify hydrogen concentration for clinical trials, and when independent certification bodies test machine output, GC or equivalent analytical instrumentation is what they use.
Digital Dissolved Hydrogen Meters
Digital dissolved hydrogen meters use an electrochemical sensor to measure H₂ concentration directly in real time. The key distinction is in the name: a "dissolved hydrogen meter" detects H₂ molecules. An "ORP meter" measures electrical potential — an unreliable proxy for hydrogen concentration per the 2022 Frontiers analysis. Both instruments look similar. What they measure is fundamentally different.
What Concentration Ranges Have Been Used in Research?
A Wide Range Across Clinical Studies
Published human trials have used hydrogen-rich water (HRW) across a broad concentration spectrum — from below 0.3 PPM to above 5 PPM. Most trials reporting measurable outcomes used concentrations in the range of approximately 0.8–3 PPM, though this is an observational pattern across the literature, not a prescribed therapeutic window.
Ohsawa et al. (2007), in the foundational preclinical study published in Nature Medicine, reported that hydrogen appeared to selectively target the hydroxyl radical and peroxynitrite without interfering with other ROS that serve beneficial signaling roles (PMID 17486089). That finding launched a decade of clinical investigation at various concentrations — which is exactly why ppm levels used in individual studies warrant careful documentation rather than generalization.
Why 1.6 PPM Keeps Appearing
The figure "1.6 PPM" recurs in hydrogen water discussions because it approximates the saturation point of molecular hydrogen in water at standard atmospheric pressure and ambient temperature. Beyond this level, hydrogen gas begins coming out of solution when a container is opened to atmosphere. It is not a therapeutic benchmark — it is a physics boundary.
Machines that claim concentrations above 1.6 PPM are either producing supersaturated water under pressure, using sealed production and delivery systems, or reporting numbers that have not been verified under open-container conditions. Understanding this helps clarify what "up to approximately 1.6 ppm under normal conditions" means when applied to an electrolysis machine operating without pressurization: it is the natural ceiling, not a marketing cap.
What "Supersaturated" Means — and Why It Matters
The Physics of H2 Solubility at Atmospheric Pressure
A supersaturated hydrogen water solution holds more dissolved H₂ than the equilibrium point for a given temperature and pressure. This is achievable through pressurized electrolysis or a sealed production environment. Machines claiming 3, 5, or 7 PPM are typically producing supersaturated water under pressure and delivering it to a sealed container.
Supersaturated solutions are inherently unstable when exposed to atmosphere. Pour one into an open glass and dissolved hydrogen begins off-gassing immediately. This makes the measurement context matter: certified machine output measured in a sealed test environment will be higher than a home test conducted in an open cup minutes after production. Neither figure is inaccurate — they are measuring different things at different moments. Recognizing this prevents consumers from incorrectly concluding that a machine is underperforming based on a home reading that simply reflects off-gassing under normal conditions.
What to Look for in a Test Certificate
When a company publishes output data for a hydrogen water machine, the supporting documentation should specify: the test method used (gas chromatography or equivalent), the conditions under which the test was conducted (water temperature, flow rate, water type), the date of testing, a unique certificate number, and the name of the independent testing body. Each of these fields answers a different question about what the number actually represents.
Claims without this documentation are difficult to evaluate objectively. "Up to 3 PPM" without a cited test method could mean the manufacturer's internal reading under ideal conditions, the peak output during a pressurized production cycle, or an ORP-derived estimate. "Approximately 134.2 mL/min hydrogen gas output under specified test conditions per Masa International Corp. Test No. MM03-6024-01" is a categorically different type of statement — one traceable to a specific certified measurement event conducted by an independent third party.
The practical upshot: certificates make claims falsifiable. Marketing language does not.
How Holy Hydrogen's Machine Was Actually Tested
The Masa International Independent Test
The Lourdes Hydrofix Premium Edition has been independently tested by Masa International Corp. (Test No. MM03-6024-01), which measured hydrogen gas output at approximately 134.2 mL/min under specified test conditions. This is a gas volume output measurement reflecting the electrolysis cell's production rate. The dissolved PPM concentration in the finished water depends on flow rate, contact time, and pressure — which is why dissolved concentration figures are reported separately under normal operating conditions rather than derived from the gas output figure alone.
Given the measurement criteria the published research implies — direct dissolved H₂ quantification, traceable test methods, and independent verification — here is how the Lourdes Hydrofix Premium Edition addresses them. You can find the Lourdes Hydrofix in our hydrogen water machine collection.
Under normal operating conditions, independent testing has measured dissolved hydrogen output at up to approximately 1.6 ppm. The company uses this qualified language deliberately: "up to approximately 1.6 ppm under normal conditions" — not a guaranteed floor, not a round number, but a verified output under documented parameters. The precision of the language reflects the same standard applied to the testing itself.
JFRL Testing: What It Confirms
The Lourdes Hydrofix also holds Japan Food Research Laboratories (JFRL) Certificate No. 23028707001-0201. This certificate addresses a different dimension of quality than hydrogen output: what the water doesn't contain. Under JFRL test conditions, selected plasticizers, BPA, iron, and titanium were not detected in the output water. This purity verification matters because electrolysis generates an electrochemical environment that, with lower-quality materials, can introduce contaminants from electrodes or internal components into the water.
The electrode materials in the Lourdes Hydrofix — high-purity titanium (TP270C grade, verified at 99.928% purity per metallurgical Certificate No. 17-MANS-0078-B) with platinum coating — are documented at the level of the raw material's steel mill certificate, not just the finished product. That documentation chain is what makes the JFRL non-detection result meaningful rather than merely claimed.
Why Concentration Consistency Over Time Matters More Than a Day-One Number
Electrode Materials and Long-Term Output
A machine that produces 1.6 PPM on day one and 0.4 PPM at month 18 has effectively changed what it delivers without disclosing it. The variable driving this degradation is electrode quality. As plating wears on lower-grade electrodes, the effective electrolysis surface changes — and with it, hydrogen output. The rate of degradation depends on base material purity and plating thickness, neither of which is typically disclosed in consumer marketing materials. We made the full case in our follow-up on why electrode quality outranks PPM as a buying spec.
Among verified Lourdes Hydrofix owners, independent field measurements have tracked output over extended periods. David Kim, a three-year owner who tested his unit independently, verified output at 1.7–1.8 PPM. Yvonne Petty, who has used her machine daily for seven years, reports it still performing like day one. These are individual accounts, not controlled tests — but they align with what the electrode material certification data would predict.
A Framework for Reading Any Hydrogen Water Spec Sheet
Given what PPM, PPB, ORP, and various testing methods actually represent, here is a practical approach to evaluating any machine's claims.
Unit verification first. Convert everything to the same unit before comparing. 1,600 PPB equals 1.6 PPM. A machine advertising the larger-looking number in PPB is making the same claim as a competitor advertising in PPM — check the arithmetic before drawing conclusions.
Test method second. If a concentration claim is not backed by gas chromatography or equivalent certified testing, treat it as unverified. ORP-derived figures are not a reliable substitute for direct dissolved hydrogen measurement. The 2022 Frontiers peer-reviewed analysis established this clearly. Ask what method was used to measure the number on the label.
Independent certification third. Third-party testing removes the manufacturer's incentive to test under optimized conditions. Look for a named testing body, a certificate number, and stated test conditions. A certificate number that can be referenced and traced is worth more than a round number with no source. The difference between "produces up to 1.6 PPM" and "approximately 1.6 ppm under normal conditions per Masa International Corp. Test No. MM03-6024-01" is the difference between a claim and a fact.
The Honest Limits of Home Testing
Consumer-grade testing with a digital hydrogen meter has real, structural limitations. Off-gassing begins the moment water is exposed to atmosphere. Sample handling technique, water temperature at time of testing, and the delay between production and measurement all reduce the reading relative to the machine's certified output. A result that comes in 15% below a manufacturer's documented figure does not necessarily mean the machine is underperforming — it may reflect the open-container test environment rather than the sealed conditions used in the certification test.
Home testing is most useful for relative comparison and ongoing monitoring. It can reliably detect whether a machine's output has shifted significantly over time. It is not a substitute for certified independent testing when making an initial purchasing decision. Use both types of data for what each is actually equipped to answer.
Connecting PPM to What the Research Actually Studied
One of the most practical applications of understanding PPM is comparing a machine's documented output to what was used in specific published studies. If a trial reports examining hydrogen water at 1.0–1.3 mg/L and the machine under consideration produces up to approximately 1.6 PPM under certified test conditions, that comparison is meaningful and grounded. If a trial used water at 0.3 PPM and a machine claims 5 PPM, those numbers describe different experimental contexts — and any extrapolation from the study's findings to the machine's effects would be speculative.
For a broader review of what the human research on hydrogen water has actually found — including the size of effects observed, the quality of trials, and where the evidence is genuinely strong versus preliminary — see our analysis of what the clinical research on hydrogen water actually shows.
FAQs: Readers' Most Common Questions on Specs
Q: Is higher PPM always better?
Not necessarily. No published research establishes a clear dose-response relationship in humans that validates "as high as possible" as a meaningful goal. A machine producing 1.2 PPM with independent certification is a more defensible purchase than one claiming 5 PPM with no disclosed test method.
Q: Why does my ORP reading show positive when I test hydrogen water?
A positive ORP reading most likely reflects pH, mineral content, or water temperature — not the absence of hydrogen. Per the 2022 Frontiers analysis, ORP is heavily confounded by non-hydrogen variables. A positive ORP does not confirm there's no dissolved hydrogen; it confirms ORP-based measurement is unreliable.
Q: What is a "good" PPM for hydrogen water?
The research doesn't define a single answer. Most published human studies used 0.8–3 PPM. No regulatory body has established a minimum effective dose.
Limitations of the Research
As of April 2026, over 2,000 peer-reviewed papers on molecular hydrogen appear in PubMed. Many human studies involve small sample sizes, short durations, and inconsistent reporting of how hydrogen concentration was verified. This makes precise comparisons across trials difficult — "1.2 PPM" in one study and "1.2 PPM" in another may not represent identically prepared water. Readers should weigh findings accordingly and consult qualified healthcare providers before making wellness decisions based on emerging research.
Further Reading
For the broader peer-reviewed literature on measuring dissolved molecular hydrogen and the concentration ranges used in human research, see PubMed's filtered results.
- Ohsawa et al. (2007), Nature Medicine. PMID: 17486089. The foundational preclinical study that first showed molecular hydrogen acts as a selective scavenger of the hydroxyl radical and peroxynitrite without disturbing reactive oxygen species the body uses for normal signaling. This paper is the reason "how much H₂ is actually in the water" became a measurement question worth answering at all.
- LeBaron, Sharpe, and Ohno (2022), International Journal of Molecular Sciences — review. PMID: 36499079. A systematic review of electrolyzed reduced water that walks through every property once attributed to ERW (negative ORP, alkaline pH, "microclusters," "active hydrogen") and concludes that dissolved H₂ is the only agent producing the observed effects. The authors specifically recommend measuring H₂ concentration rather than relying on ORP.
- LeBaron, Sharpe, and Ohno (2022), International Journal of Molecular Sciences — review. PMID: 36498838. The companion review covering safety and effectiveness of electrolyzed reduced water as a hydrogen source. The authors emphasize that ERW's H₂ concentration is often well below the range used in clinical trials and explicitly advise readers to avoid ORP or ORP-based meters when verifying dissolved hydrogen.
- Hatae and Miwa (2021), Medical Gas Research. PMID: 33818445. A direct measurement study of an electrolytic hydrogen-generating bottle, reporting dissolved H₂ at 444 µg/L after 10 minutes of electrolysis and 479 µg/L after 30 minutes, alongside an ORP of -245 mV. A useful real-world data point showing how PPB-scale readings translate to ORP readings and how the two numbers move together but measure different things.
- Ohta (2014), Pharmacology & Therapeutics — review. PMID: 24769081. A broad review of molecular hydrogen as a medical gas, covering the delivery routes studied (inhalation, hydrogen-rich water, saline) and the concentration ranges examined across animal and human studies. Helpful context for understanding why "how much H₂ at the point of consumption" became the central practical question.
- Ichihara et al. (2015), Medical Gas Research — review. PMID: 26483953. A review of 321 original molecular hydrogen articles published through mid-2015, summarizing reported effects across organ systems and disease models. The paper documents the wide range of H₂ concentrations and delivery formats used across the literature — useful when comparing a machine's documented output to specific studies.
References
- Ohsawa, I., Ishikawa, M., Takahashi, K., et al. (2007). Hydrogen acts as a therapeutic antioxidant by selectively reducing cytotoxic oxygen radicals. Nature Medicine, 13, 688–694. PMID: 17486089.
- Nakao, A., et al. (2010). Effectiveness of hydrogen rich water on antioxidant status of subjects with potential metabolic syndrome — an open label pilot study. Journal of Clinical Biochemistry and Nutrition, 46(2), 140–149. PMID: 20216947.
- Frontiers in Food Science and Technology. (2022). ORP should not be used to estimate or compare concentrations of aqueous H2: An in silico analysis and narrative synopsis. DOI: 10.3389/frfst.2022.1007001.
Holy Hydrogen products, including the Lourdes Hydrofix Premium Edition, are not medical devices and are not intended to diagnose, treat, cure, or prevent any disease. All information on this site is provided for educational and general wellness purposes only and should not be considered medical advice. Always consult a qualified healthcare provider before beginning any new wellness practice, especially if you have a medical condition, are pregnant or nursing, or take prescription medications.
Given these criteria — direct dissolved H₂ measurement, certified gas chromatography or equivalent testing, traceable certificate numbers, and independent third-party verification — here is how the Lourdes Hydrofix Premium Edition answers them. The engineering case starts with the documentation: certified electrode materials, an independent gas output test with a traceable certificate number, JFRL purity verification, and a track record of owner-verified output across years of daily use. If you've read this article and want to see how those specifics translate to a machine you can use at home, the full technical details are available on the Lourdes Hydrofix Premium Edition product page.