Dropping a piece of metallic magnesium into water triggers a straightforward chemical reaction that releases dissolved hydrogen gas, and this is the oldest and simplest method people use to make hydrogen-rich water at home. The reaction produces magnesium hydroxide as a byproduct, which raises the water’s pH and has its own implications for taste and safety. While the process sounds as easy as tossing a metal stick into a glass, getting a meaningful concentration of dissolved hydrogen and keeping the water drinkable involves more nuance than most product labels suggest.
The Chemistry Behind the Reaction
When metallic magnesium contacts water, it reacts to form magnesium hydroxide and hydrogen gas. The equation is simple: one atom of magnesium reacts with two molecules of water, yielding magnesium hydroxide and one molecule of hydrogen gas. An open-label pilot study used exactly this method, placing a metallic magnesium stick into drinking water and achieving a dissolved hydrogen concentration of roughly 0.55 to 0.65 millimolar (about 1.1 to 1.3 parts per million).1PubMed Central. Effectiveness of Hydrogen Rich Water on Antioxidant Status of Subjects with Potential Metabolic Syndrome—An Open Label Pilot Study
The catch is that this reaction is naturally sluggish at room temperature. Pure magnesium in plain water reacts slowly because a thin layer of magnesium oxide or hydroxide forms on the metal’s surface almost immediately, acting like a shield that slows further contact with the water. Research on the reaction mechanism has shown that the process speeds up considerably when powdered magnesium is combined with a small amount of iron and the water contains some dissolved salt.2The Journal of Physical Chemistry A. Mechanism of Dihydrogen Formation in the Magnesium−Water Reaction This is why commercial magnesium sticks and tablets often contain trace amounts of other metals or are formulated with specific additives: they are engineered to overcome that passivation layer and keep the reaction going.
What You Actually Need and How to Do It
The most common consumer approach uses a magnesium stick, which is a sealed mesh pouch or perforated metal casing containing magnesium granules or pellets. You drop the stick into a sealed bottle of water, wait, and drink. Here is what matters at each step.
- Water container: Use a bottle you can seal tightly. Hydrogen gas escapes from open containers within minutes. A glass or BPA-free plastic bottle with a screw cap works. Avoid containers with wide openings you cannot close.
- Water temperature: Room-temperature or slightly warm water reacts faster than cold water. Very hot water is counterproductive because while the reaction speeds up, the solubility of hydrogen gas in water actually drops at higher temperatures, meaning more of the gas escapes rather than staying dissolved.3International Journal of Hydrogen Energy. Hydrogen solubility in aqueous solutions: A thermodynamic modeling approach using electrolyte equation of state
- Reaction time: Most magnesium sticks need anywhere from 6 to 12 hours to produce a meaningful dissolved hydrogen concentration. Some manufacturers claim shorter times, but the passivation issue means the first hour produces much less hydrogen than the later hours. Overnight soaking is the most practical approach.
- Seal the bottle: Once you drop the stick in, cap it. The dissolved hydrogen will reach equilibrium with the gas above the water. An unsealed bottle loses hydrogen rapidly because dissolved Hâ‚‚ diffuses out of solution and into the air.
Effervescent magnesium tablets work on the same principle but are designed to react much faster. These tablets typically combine magnesium with an acid source and sometimes other excipients to accelerate gas release. Research into hydrogen-generating effervescent tablets has found that the choice of filler material affects both how quickly the tablet dissolves and how much hydrogen it releases, with certain sugar alcohols promoting faster generation.4PubMed Central. Formulation and Characterization of an Effervescent Hydrogen-Generating Tablet Tablets generally produce hydrogen in a few minutes rather than hours, but much of that gas can bubble away before you drink it unless you dissolve the tablet in a sealed container and drink promptly.
How Much Hydrogen Actually Stays in the Water
Dissolved hydrogen concentration is the number that matters, and it is harder to control than you might expect. At standard atmospheric pressure and room temperature, water can hold roughly 1.6 parts per million (ppm) of dissolved hydrogen at saturation. Most magnesium stick methods produce somewhere between 0.5 and 1.3 ppm, depending on how long the stick has been soaking, whether the container was sealed, and how fresh the magnesium is.1PubMed Central. Effectiveness of Hydrogen Rich Water on Antioxidant Status of Subjects with Potential Metabolic Syndrome—An Open Label Pilot Study
Once you open the bottle, dissolved hydrogen starts escaping immediately. Think of it like a carbonated drink losing its fizz: hydrogen is even lighter and less soluble than carbon dioxide, so the clock is ticking faster. Drinking within a few minutes of opening gives you the most hydrogen. Pouring the water into a separate glass and letting it sit on a counter for ten minutes means you are drinking water with substantially less dissolved hydrogen than what was in the sealed bottle.
Temperature also plays a role that trips people up. Solubility modeling shows that hydrogen’s behavior in water is not linear with temperature. At constant pressure, solubility first decreases as water warms, then increases again at much higher temperatures. For practical purposes at home, cooler water holds more dissolved hydrogen than warm water, so refrigerating your sealed bottle after the magnesium has reacted is a reasonable strategy.
The Byproduct Problem: Magnesium Hydroxide
Every molecule of hydrogen gas produced by this reaction is accompanied by magnesium hydroxide. That is not a minor footnote; it changes the water’s character. Magnesium hydroxide is a mild base commonly sold as milk of magnesia. In small amounts, it raises the pH of your water and can give it a slightly chalky or mineral taste. In larger amounts, it acts as a laxative.
This means the amount of magnesium hydroxide in your water depends directly on how much hydrogen was produced. A stick that generates a good hydrogen concentration is also generating a proportional amount of alkaline byproduct. For most healthy adults, the quantities involved from a single bottle are not concerning, but people who use magnesium sticks in multiple bottles per day should be aware that they are consuming magnesium hydroxide on top of whatever magnesium they get from food and supplements. If you already take magnesium supplements or have kidney issues that affect magnesium excretion, this matters.
Corrosion research on magnesium shows that the protective hydroxide film that forms on the metal surface is unstable in any water that is not strongly alkaline (above about pH 10.5), and it breaks down faster when chloride ions are present.5Elsevier. A study on magnesium corrosion by real-time imaging and electrochemical methods: relationship between local processes and hydrogen evolution This is relevant because some people add a pinch of salt to their water to speed up the reaction. It works — the chloride in salt does accelerate magnesium corrosion and hydrogen production — but it also increases the breakdown products in the water. The tradeoff is faster hydrogen generation at the cost of a potentially cloudier, more mineral-laden result.
Purity and What Else Ends Up in Your Water
Not all magnesium is created equal. Industrial-grade magnesium can contain trace amounts of other metals, including potentially harmful ones like cadmium, lead, and nickel. A study examining magnesium oxide preparations sold commercially found that elemental impurity levels varied across products, and while all met international safety guidelines overall, some preparations had cadmium levels that exceeded the stricter 30% control threshold when taken at maximum daily dosage.6J-STAGE / Drug Discoveries & Therapeutics. Study of the compatibility of oral magnesium oxide preparations sold in Japan with the ICH-Q3D guideline for elemental impurities
The relevance here is straightforward. If you are buying a magnesium stick marketed for making hydrogen water, the purity of the magnesium matters because whatever is in that metal is dissolving into your drinking water. Products from reputable manufacturers that specify food-grade or pharmaceutical-grade magnesium are a safer bet than cheap, unbranded sticks from anonymous online sellers. There is no regulation in most countries that specifically covers “hydrogen water sticks” as a product category, so the burden of checking purity falls on you.
Why People Bother: What Dissolved Hydrogen Might Do
The interest in hydrogen water stems from research suggesting that dissolved molecular hydrogen acts as a selective antioxidant. A landmark 2007 study demonstrated that hydrogen gas selectively neutralizes hydroxyl radicals, which are among the most damaging reactive oxygen species in the body, without interfering with other reactive oxygen species that serve normal biological functions like cell signaling.7PubMed. Hydrogen acts as a therapeutic antioxidant by selectively reducing cytotoxic oxygen radicals Since that paper, the beneficial effects of molecular hydrogen have been studied in over 170 disease models and human conditions, including metabolic disorders and inflammation.8PubMed. Molecular hydrogen: current knowledge on mechanism in alleviating free radical damage and diseases
Beyond direct radical scavenging, a systematic review noted that molecular hydrogen appears to suppress inflammatory signaling and activate the body’s own antioxidant defense pathways.9PubMed Central. Hydrogen Water: Extra Healthy or a Hoax?—A Systematic Review A controlled trial in healthy adults found that those drinking hydrogen-rich water showed reduced expression of genes involved in inflammatory signaling pathways, along with lower levels of several inflammatory markers.10Scientific Reports. Hydrogen-rich water reduces inflammatory responses and prevents apoptosis of peripheral blood cells in healthy adults: a randomized, double-blind, controlled trial These are intriguing findings, though it is worth noting that much of the research involves relatively small sample sizes and short durations, and the field is still sorting out which effects hold up at scale.
Clinical Findings on Metabolic Health
Some of the more concrete clinical data comes from trials in people with metabolic problems. In a 24-week randomized controlled trial, people with metabolic syndrome who drank high-concentration hydrogen-rich water experienced drops in total cholesterol of about 18.5 mg/dL, triglyceride reductions of roughly 47 mg/dL, and a decrease in fasting blood glucose. Their inflammatory markers also improved significantly compared to the placebo group.11Diabetes, Metabolic Syndrome and Obesity. The Effects of 24-Week, High-Concentration Hydrogen-Rich Water on Body Composition, Blood Lipid Profiles and Inflammation Biomarkers in Men and Women with Metabolic Syndrome: A Randomized Controlled Trial
An earlier study in patients with type 2 diabetes or impaired glucose tolerance found that hydrogen-rich water intake was linked to a roughly 15% decrease in modified LDL cholesterol and a decrease in urinary markers of oxidative stress. In four out of six participants with impaired glucose tolerance, hydrogen-rich water normalized their glucose tolerance test results.12PubMed. Supplementation of hydrogen-rich water improves lipid and glucose metabolism in patients with type 2 diabetes or impaired glucose tolerance These are encouraging numbers, but the sample sizes were small. Nobody should treat hydrogen water as a replacement for established treatments for diabetes or high cholesterol. The evidence points to a possible supportive role, not a cure.
Effects on Gut Bacteria
An unexpected research thread has emerged around hydrogen water and the gut microbiome. Your intestines already produce substantial amounts of hydrogen gas through bacterial fermentation. Drinking hydrogen-rich water appears to change the balance of gut bacteria in ways that differ from simply inhaling hydrogen gas. In a rat study, animals that drank hydrogen-rich water showed significant shifts in their gut bacterial communities, including increased abundance of beneficial bacteria like Lactobacillus, while animals that inhaled the same amount of hydrogen showed no such changes.13PubMed Central. Different effects of hydrogen-rich water intake and hydrogen gas inhalation on gut microbiome and plasma metabolites of rats in health status
The proposed explanation is that drinking hydrogen-rich water delivers extra hydrogen directly to the gut, where it acts as a supplemental fuel source for hydrogen-consuming microbes. Certain groups of bacteria in the large intestine use hydrogen for their own metabolism, and providing them with more of it may selectively boost their populations.14Journal of Functional Foods. Hydrogen-rich water as a modulator of gut microbiota? This is an area where the science is genuinely early-stage, but it raises the interesting possibility that the route of hydrogen delivery (drinking vs. inhaling) matters more than researchers initially assumed.
Magnesium Sticks Versus Tablets Versus Electrolysis
Making hydrogen water with magnesium is just one approach. Electrolysis machines split water molecules using an electric current, producing hydrogen at the cathode. These devices are more expensive (ranging from a hundred to several hundred dollars) but generate hydrogen on demand and do not leave chemical byproducts in the water. Effervescent tablets containing magnesium and acid react in minutes, offering a portable middle ground. Each method has tradeoffs worth understanding.
Magnesium sticks are the cheapest option. A single stick typically costs a few dollars and can be reused for weeks or months, though hydrogen output declines as the magnesium corrodes and the surface becomes coated. The main drawbacks are the long reaction time and the magnesium hydroxide byproduct. You are also limited in how high you can push the dissolved hydrogen concentration because the reaction rate is inherently slow.
Tablets dissolve and react in minutes, making them more practical when you want hydrogen water on the go. In clinical trials studying hydrogen water’s effects, tablets are commonly used as the delivery method because researchers can standardize the dose. Some trial designs even use visually identical placebo tablets to maintain blinding, matching the effervescence and taste profile of the active tablets.15PubMed Central. Hydrogen-Rich Water Decreases Muscle Damage and Improves Power Endurance in Elite Athletes: A Randomized, Double-Blinded, Placebo-Controlled Trial Tablets generally achieve higher and more consistent hydrogen concentrations than sticks, but they are a recurring cost and still produce magnesium compounds in the water.
Electrolysis machines produce hydrogen without adding magnesium or any other chemical to the water. The dissolved hydrogen concentration can be higher and more controllable. The water’s mineral content and pH remain essentially unchanged. The downside is cost and the fact that you need electricity, making them less portable. For someone who plans to drink hydrogen water daily over months or years, the math on an electrolysis machine may work out better than a continuous supply of tablets.
Common Mistakes and How to Avoid Them
The most frequent error people make is leaving the container open. An uncapped bottle of hydrogen water loses a large fraction of its dissolved hydrogen in under 30 minutes. If you are going through the trouble of making it, drink it from the sealed container or pour and drink immediately.
Using hot water is another common misstep. People assume heat speeds up the reaction (it does, slightly) and therefore produces better results. But the loss of dissolved hydrogen to the gas phase at higher temperatures more than offsets the faster reaction rate. Stick with room temperature or cooler water and let the magnesium do its slow work.
Reusing a magnesium stick past its useful life is also an issue. Over time, the surface becomes coated with corrosion products and the reaction slows to a crawl. If your water no longer develops any visible micro-bubbles on the stick’s surface after several hours, the stick is spent. Some manufacturers recommend replacing sticks every three to six months depending on frequency of use.
Finally, people sometimes assume that more magnesium means more hydrogen. Dropping three sticks into one bottle does increase the total surface area available for reaction, but the water can only hold so much dissolved hydrogen at atmospheric pressure. Beyond saturation, extra gas just bubbles out. You hit diminishing returns fast, and you end up with water that has an unnecessarily high magnesium hydroxide load.
Who Should Think Twice
People with chronic kidney disease need to be cautious. The kidneys are responsible for excreting excess magnesium, and impaired kidney function can lead to magnesium buildup. Since the magnesium stick method adds magnesium hydroxide to your water with every use, daily consumption could contribute to hypermagnesemia in someone whose kidneys are not clearing magnesium efficiently.
Anyone taking medications that interact with magnesium should also pay attention. Magnesium hydroxide can interfere with the absorption of certain antibiotics, bisphosphonates, and thyroid medications. If you take prescription drugs on a regular schedule, drinking magnesium-produced hydrogen water around the same time as your medication could reduce how well the drug works.
Pregnant or breastfeeding women are another group with reason to be careful, not because hydrogen itself has shown any evidence of harm, but because the magnesium hydroxide intake adds an uncontrolled variable to an already carefully managed set of nutritional requirements. Using an electrolysis-based device, which does not add minerals to the water, avoids this issue entirely.
For healthy adults with normal kidney function and no relevant medication interactions, the magnesium hydroxide amounts from one or two bottles per day are well within the range that the body handles without difficulty. The laxative effect of magnesium hydroxide is dose-dependent, and the amounts produced by a single stick in a standard bottle of water fall far below what you would get from a therapeutic dose of milk of magnesia. Still, if you notice looser stools after starting hydrogen water, the magnesium hydroxide byproduct is the most likely explanation.