Hydrogen Water Glossary: PPB, PPM, SPE, PEM, and Every Term Explained
Why This Page Exists
The hydrogen water market is full of acronyms and technical terms that brands throw around in their marketing. PPB, PPM, SPE, PEM, ORP, IHSA, DuPont membrane. Some of these matter. Some are marketing noise. This glossary explains every term you’ll encounter when shopping for hydrogen water products, in plain language.
Bookmark this page. Come back whenever a product listing uses a term you don’t recognize.
Concentration and Measurement
PPB (Parts Per Billion) The standard unit for measuring dissolved hydrogen concentration in water. 1,000 PPB = 1 PPM. Most clinical studies showing health benefits used water between 500-1,500 PPB. When we review products, PPB is the primary performance metric. Higher is generally better, but anything above 1,000 PPB clears the therapeutic threshold. Learn how to measure PPB at home →
PPM (Parts Per Million) Same as PPB but on a different scale. 1 PPM = 1,000 PPB = 1 mg/L. Some brands use PPM, others use PPB. Just multiply or divide by 1,000 to convert. A product claiming “3.0 PPM” is claiming 3,000 PPB.
mg/L (Milligrams Per Liter) Another way to express concentration. 1 mg/L = 1 PPM = 1,000 PPB. Lab reports typically use mg/L. Product marketing typically uses PPB (because bigger numbers look more impressive).
Saturation Point The maximum amount of hydrogen gas that can dissolve in water at a given temperature and pressure. At room temperature and normal atmospheric pressure, the saturation point is approximately 1.6 PPM (1,600 PPB). Any product claiming to exceed this in an open container at room temperature is either using pressurization, supersaturation techniques, or inflating their numbers. More on PPB claims →
ORP (Oxidation-Reduction Potential) Measured in millivolts (mV). A negative ORP indicates antioxidant potential. Hydrogen water typically has ORP between -300 and -600 mV. Some brands highlight ORP as a selling point, but PPB is a more direct and useful measurement of hydrogen content. A product with great ORP but low PPB isn’t delivering much dissolved hydrogen.
Therapeutic Threshold The minimum hydrogen concentration shown to produce health effects in clinical studies. Generally cited as 0.5-1.0 PPM (500-1,000 PPB). Products below 500 PPB may not deliver enough hydrogen for measurable benefit. Our recommendation: aim for 1,000+ PPB consistently.
Technology Terms
SPE (Solid Polymer Electrolyte) A type of membrane used in hydrogen water generators. The SPE membrane conducts protons (hydrogen ions) while separating hydrogen gas from oxygen and other byproducts. It’s one half of the SPE/PEM technology pair that defines quality hydrogen generators.
PEM (Proton Exchange Membrane) Works with SPE technology to separate hydrogen from oxygen during electrolysis. The PEM selectively passes protons while blocking other molecules, ensuring the hydrogen gas that dissolves into your water is pure. “SPE/PEM technology” is the industry standard for quality hydrogen generators. If a product doesn’t mention SPE/PEM, it’s likely using basic electrolysis without membrane separation, which can introduce ozone and other unwanted byproducts.
Electrolysis The process of using electrical current to split water molecules (H₂O) into hydrogen gas (H₂) and oxygen gas (O₂). This is how all hydrogen water generators work. Electrolysis is established chemistry — nothing proprietary or mysterious about it. What varies is the quality of the electrodes, membranes, and chamber design.
Electrode Plates The metal components inside the generator that conduct electricity through the water to trigger electrolysis. Quality generators use platinum-coated titanium plates. These are resistant to corrosion, produce clean hydrogen, and last longer than cheaper alternatives. Some budget products use nickel or stainless steel electrodes that can degrade and contaminate the water over time.
DuPont Membrane (Nafion) Some brands specifically mention using DuPont Nafion membranes in their PEM technology. Nafion is a widely used, well-regarded ion exchange membrane. It’s a quality indicator but not a magic ingredient. Other manufacturers make comparable membranes. “DuPont membrane” in marketing signals quality materials, similar to how “Gorilla Glass” signals quality in phones.
Dual Chamber / Separated Chamber A design where the hydrogen generation chamber is physically separated from the drinking water chamber, with the PEM membrane between them. This prevents byproducts (ozone, chlorine residue) from mixing into the water you drink. Better generators use dual-chamber designs. Budget products sometimes use single-chamber designs where everything mixes together.
Product Terms
Cycle Time How long the generator runs to produce one batch of hydrogen water. Typical range: 3-13 minutes. Shorter cycles produce less hydrogen. Longer cycles produce more. Most products offer two modes (quick 3-5 min, deep 10-13 min).
Retention Time How long hydrogen stays dissolved in the water after generation. Typical range: 15-120 minutes before concentrations drop below therapeutic levels. Sealed containers retain hydrogen longer than open glasses. Drink it fresh for maximum benefit.
Self-Cleaning Mode A reverse-polarity electrolysis cycle that removes mineral deposits from the electrode plates. Some generators include this feature (IonBottles Pro, Piurify). Others require manual citric acid soaking. Self-cleaning modes extend electrode life and maintain consistent PPB output.
Auto-Polarity Reversal A feature where the electrode polarity reverses with each generation cycle, preventing mineral buildup naturally. The Echo Go+ uses this approach, reducing the frequency of manual descaling.
Certifications and Standards
IHSA (International Hydrogen Standards Association) An organization that certifies hydrogen water products for hydrogen output accuracy and safety. IHSA certification means a third party verified the product actually produces the hydrogen it claims. The Echo Flask has IHSA certification. Not all products do. It’s a positive signal when present.
H2 Analytics / H2HUBB Independent labs that test hydrogen water products and issue certification reports. When a brand references an “H2 Analytics lab report,” it means a third party measured their hydrogen output. These reports are more reliable than manufacturer self-testing. Dr. Water products are H2HUBB certified.
BPA-Free Means the product doesn’t contain Bisphenol A, a chemical used in some plastics that can leach into water. All products we review are BPA-free. This is a minimum standard, not a differentiator.
FDA GRAS (Generally Recognized As Safe) The FDA classifies hydrogen gas as GRAS when used as a food additive. This means hydrogen water is considered safe to consume. It’s not an “FDA approval” in the medical sense (hydrogen water is not approved to treat or cure anything), but it confirms safety.
Marketing Terms (Approach With Skepticism)
“Structured Water” A claim that water molecules can be reorganized into hexagonal or otherwise “structured” formations with health benefits. The scientific evidence for structured water is extremely thin. Some brands (like Piurify with their vortex feature) reference structured water. The vortex is useful for mixing and byproduct removal. The “structured water” claim is mostly marketing.
“Alkaline Hydrogen Water” Some electrolysis generators produce both hydrogen and alkaline pH simultaneously. The hydrogen is the component with clinical evidence. The alkalinity is a byproduct, not an additional benefit. Read our alkaline vs. hydrogen water breakdown →
“Molecular Hydrogen Therapy” A term used by some brands and practitioners to position hydrogen water as a therapeutic intervention. While hydrogen water has research-backed benefits, “therapy” implies medical treatment. Hydrogen water is a supplement, not a medical therapy. Be cautious with brands that use medical framing.
“Nano-Bubbles” Some brands claim their generators produce “nano-bubbles” of hydrogen that stay dissolved longer. The physics is real (smaller bubbles dissolve more completely), but the marketing often overstates the practical difference. What matters is the measured PPB in your water, not the bubble size.
FAQ
What’s the most important term to understand? PPB. It’s the core performance metric. Everything else is secondary. A product that hits 1,000+ PPB consistently with SPE/PEM technology is doing its job.
Do I need to understand all these terms to buy a hydrogen water product? No. Check the PPB output (ideally independently tested), confirm SPE/PEM technology, verify the warranty, and you’re covered. Everything else is detail for people who want to go deeper.
What’s the difference between PPB and PPM? Just scale. 1,000 PPB = 1 PPM. Brands use PPB because “~1,500 PPB” sounds more impressive than “1.4 PPM.” Same hydrogen, different number.
WaterTechReview earns commissions from qualifying purchases through the links above. This doesn’t influence our ratings or recommendations. How we test →