Alkaline water is water with a pH higher than 7, typically ranging from 8 to 9.5. On the pH scale, which runs from 0 (most acidic) to 14 (most alkaline), regular tap water sits around 7, or neutral. Alkaline water gets its higher pH either from naturally occurring minerals or from an artificial process that alters the water’s chemistry.
How Alkaline Water Is Made
There are two main ways alkaline water ends up in your glass. The first is natural: water flows through rock formations and picks up minerals like calcium, magnesium, and potassium along the way. Some artesian springs produce water with a naturally elevated pH and dissolved bicarbonate. This is the kind of alkaline water that has existed for as long as people have been drinking from mineral springs.
The second method is electrolysis, sometimes marketed as “ionized” water. A device called a water ionizer runs an electrical current through tap water, separating it into two streams. One stream concentrates hydroxide ions, raising the pH. The other stream becomes more acidic and is discarded. Bottled alkaline water sold in stores may also simply have minerals like calcium and magnesium added after purification to bump up the pH.
What the Science Says About Benefits
Most health claims around alkaline water are either preliminary or based on lab and animal studies that haven’t been confirmed in people. That said, a few specific findings are worth knowing about.
The strongest lab evidence involves acid reflux. A 2012 study found that water with a pH of 8.8 permanently inactivated pepsin, the stomach enzyme that damages throat and esophageal tissue during reflux episodes. Regular drinking water doesn’t do this. The implication is that alkaline water could be a useful addition to reflux management, though large-scale human trials haven’t followed up on this finding.
A study on hydration measured blood viscosity (how thick and slow-moving your blood is) in healthy adults after exercise-induced dehydration. Those who drank electrolyzed high-pH water saw their blood viscosity drop by 6.3%, compared to 3.36% with standard purified water. That difference was statistically significant. However, every other hydration marker the researchers checked, including plasma concentration, body water content, and body mass change, showed no difference between the two groups. So the water rehydrated people equally well by most measures.
Animal research on blood sugar is intriguing but very early. Diabetic rats given alkaline reduced water had notably lower blood glucose levels than diabetic rats drinking regular water. The mechanism appeared to involve reduced activity of an enzyme that breaks down sugars for absorption. No human clinical trials have replicated this, so it remains a laboratory observation, not a treatment recommendation.
Bone Health Claims Lack Support
You may have seen claims that alkaline water protects your bones by reducing the acid load your body has to neutralize. The theory goes that a less acidic internal environment means your body pulls fewer minerals from your skeleton. The FDA evaluated a related health claim about alkaline compounds and osteoporosis risk and declined to approve it, noting that the proposed mechanism (bone resorption) doesn’t qualify as a disease endpoint under their standards. No credible regulatory body currently recognizes alkaline water as bone-protective.
Potential Risks of High-pH Water
The EPA recommends a pH range of 6.5 to 8.5 for drinking water. The Mayo Clinic flags safety concerns for water with a pH above 9.8, which some commercial products and home ionizers can reach.
The main worry is what happens to digestion. Your stomach maintains a highly acidic environment for good reason: it breaks down protein, activates digestive enzymes, and enables absorption of vitamin B12 and several minerals including iron and calcium. Consistently neutralizing that acid, whether through alkaline water or chronic antacid use, can lead to a condition called hypochlorhydria, or low stomach acid. The downstream effects include poor protein digestion, B12 deficiency, and iron deficiency anemia. This doesn’t mean a glass of pH 8 water will cause problems, but routinely drinking large volumes of highly alkaline water could theoretically interfere with normal digestion over time.
Alkaline water can also reduce the effectiveness of certain medications that depend on stomach acid for proper absorption. If you take prescription medications regularly, this is worth considering.
How It Compares to Regular Water
For most people, the minerals in alkaline water (calcium, magnesium, potassium) are the same ones found in a balanced diet and in many municipal water supplies. Tap water in most U.S. cities already falls within the 6.5 to 8.5 pH range the EPA recommends. The practical difference between drinking that and bottled alkaline water at pH 8 or 9 is minimal for someone who is otherwise healthy and eating well.
Where alkaline water might offer a small edge is in very specific situations: as a complement to reflux management, or possibly for post-exercise rehydration. Even in those cases, the evidence is thin enough that no major medical organization recommends it as a treatment. The most reliable way to stay hydrated and get adequate minerals is still plain water and a varied diet. If you enjoy alkaline water and stick to products with a pH under 9.8, there’s little evidence of harm, but the proven benefits remain modest at best.