Alkaline water is water with a pH higher than regular drinking water, typically around 8 or 9 on the pH scale. For comparison, the EPA recommends a pH range of 6.5 to 8.5 for municipal tap water, and pure water sits at a neutral 7.0. The higher pH comes from dissolved minerals like calcium, magnesium, potassium, and iron. Whether that elevated pH delivers meaningful health benefits is where things get complicated.
How Alkaline Water Is Made
There are two main ways to produce alkaline water, and the method matters because each creates a slightly different product.
The first is electrolysis. Water ionizer machines use electricity to run water over positive and negative electrodes, which separates the acidic and alkaline minerals already present in the water. This produces two streams: one alkaline, one acidic. Electrolyzed water tends to have a negative oxidation-reduction potential (ORP), meaning it acts as a reducing agent rather than an oxidizing one. Proponents argue this gives it antioxidant properties, though that claim is far from settled science.
The second method is mineral addition. These systems use filters that infuse water with alkaline minerals while removing contaminants. They’re simpler, less expensive, and don’t require electricity. The tradeoff is less control over the final pH and a less negative ORP value compared to electrolyzed water.
You can also buy pre-bottled alkaline water, which is typically alkalized through one of these two processes or sourced from natural springs that pick up minerals as water flows over rock.
What the Research Actually Shows
Most health claims around alkaline water are either preliminary or overstated. But a few areas of research have produced interesting, if limited, findings.
Acid Reflux
The most specific evidence involves acid reflux. Pepsin, the enzyme responsible for protein digestion in your stomach, is also the main culprit behind the tissue damage in reflux disease. Pepsin becomes active at a pH below 4.5 and does its damage to the throat and esophagus when stomach contents travel upward. A lab study published in ENTtoday found that alkaline water with a pH of 8.8 permanently inactivated pepsin. That’s a meaningful distinction from simply neutralizing acid temporarily the way an antacid does. However, this was demonstrated in a test tube, not inside a human body, where stomach acid would likely lower the water’s pH before it could have the same effect.
Post-Exercise Hydration
A study in the Journal of the International Society of Sports Nutrition measured blood viscosity in healthy adults after exercise-induced dehydration. Thicker blood is harder for the heart to pump and slower to deliver oxygen. Participants who drank electrolyzed high-pH water saw their blood viscosity drop by an average of 6.3%, compared to 3.36% with standard purified water. That’s a statistically significant difference, though it’s a single study with a small sample and the practical impact on athletic performance hasn’t been established.
Bone Health
A study of 30 women compared two types of calcium-rich mineral water: one acidic, one alkaline and rich in bicarbonate. Both groups ate the same diet with adequate calcium intake. After four weeks, the group drinking alkaline bicarbonate-rich water showed significant decreases in two markers of bone breakdown (parathyroid hormone and a protein fragment released when bone tissue is dismantled). The acidic water group showed no change. This suggests that the alkalinity, not just the calcium content, played a role. But reducing markers of bone loss in a four-week study is a long way from preventing osteoporosis over a lifetime.
How Your Body Handles pH
Your body maintains blood pH within a remarkably tight range of 7.35 to 7.45. It does this through your lungs (which expel carbon dioxide) and your kidneys (which filter excess acids and bases). This system is powerful and largely automatic. Drinking a glass of pH 9 water won’t shift your blood pH in any measurable way, which is actually a good thing, because even small deviations from that range can be dangerous.
Your stomach, meanwhile, operates at a pH between 1.5 and 3.5, acidic enough to break down food and kill bacteria. When alkaline water hits your stomach, it gets neutralized quickly. This is why lab findings about pepsin inactivation don’t automatically translate to clinical benefits: the alkaline water may never reach reflux-damaged tissue at its original pH.
Potential Risks of Overconsumption
For most healthy people, drinking alkaline water in normal amounts is unlikely to cause harm. The real risks emerge with excessive consumption or in people with compromised kidney function.
The concern is metabolic alkalosis, a condition where blood becomes too basic. Healthy kidneys can easily handle a modest alkaline load, but kidneys that aren’t functioning well may struggle to correct the imbalance. Symptoms of mild metabolic alkalosis include nausea, vomiting, tingling or numbness, and muscle cramping. Severe cases can cause confusion, abnormal heart rhythms, kidney damage from electrolyte imbalance, and in rare instances, seizures or coma.
Alkaline water can also lower stomach acidity enough to interfere with digestion if consumed in large quantities with meals. Your stomach needs that low pH to activate digestive enzymes and kill pathogens in food.
What It Won’t Do
The broadest claim about alkaline water is that it “alkalizes your body” and that an alkaline internal environment prevents cancer, slows aging, and cures chronic disease. This misunderstands basic physiology. Your body’s pH regulation systems don’t allow dietary changes to meaningfully shift blood pH, and the premise that cancer thrives only in acidic environments is a distortion of the underlying science. Cancer cells do produce lactic acid as a metabolic byproduct, but that’s a consequence of the disease, not a cause that can be reversed by drinking different water.
Claims about superior antioxidant properties are based on the negative ORP of ionized water, which does indicate reducing potential in a lab setting. But there’s no strong clinical evidence that drinking negative-ORP water delivers antioxidant effects comparable to, say, eating a bowl of berries.
Is It Worth Drinking?
If you enjoy the taste of alkaline water and it encourages you to drink more water overall, there’s no reason to avoid it. The minerals it contains, particularly calcium and magnesium, are genuinely beneficial, though you can get the same minerals from food and regular mineral water. The early research on acid reflux and post-exercise hydration is intriguing but far too limited to justify switching your entire water supply. The most honest summary: alkaline water is water with some extra minerals. It’s not harmful for healthy people, and it’s not the health breakthrough its marketing suggests.