Most still mineral water is not acidic. It typically falls between pH 6.5 and 8.5, making it neutral to slightly alkaline. Sparkling mineral water is a different story: the carbonation process drops the pH to around 3.5 to 6, pushing it into mildly acidic territory. The distinction between still and sparkling matters more than most people realize.
How Carbonation Makes Water Acidic
Carbon dioxide is what creates the bubbles in sparkling water, but it also changes the chemistry. When CO2 dissolves in water, it reacts to form carbonic acid. This is a weak acid, but it’s enough to lower the pH significantly. Still water sits close to neutral (pH 7), while carbonated water can drop to a pH of about 3.5 in some cases.
This acidity is temporary. Once you open a bottle and the carbonation starts escaping, the pH gradually rises back toward neutral. And inside your body, the carbonic acid breaks down quickly. Your blood’s buffering system neutralizes it within minutes, so drinking sparkling mineral water doesn’t make your body more acidic in any lasting way.
pH Levels of Popular Brands
Still mineral water brands vary quite a bit depending on their mineral content and source. Lab testing of major brands shows a wide range:
- Evian: pH 7.9
- Volvic: pH 7.5
- Fiji: pH 7.3
- VOSS: pH 7.6
- Icelandic: pH 8.4
- Poland Spring: pH 7.2
- Essentia: pH 9.4
For comparison, some purified water brands actually lean slightly acidic. Dasani tests at pH 5.6 and Aquafina at pH 5.5. That’s because the purification process strips out the dissolved minerals that would otherwise keep the pH closer to neutral. Mineral water, by definition, retains those minerals, which is why it tends to be neutral or alkaline.
Why Minerals Push the pH Up
The dissolved minerals in natural mineral water act as a buffer against acidity. Bicarbonate, calcium, and carbonate are the main players. Bicarbonate in particular is the same compound your body uses in its own acid-buffering system, and water that’s rich in it consistently tests at higher pH levels.
Water with high alkalinity (a measure of bicarbonate, carbonate, and hydroxide content) resists pH changes and tends to stay neutral or above. This is why mineral water sourced from limestone or volcanic rock often reads as slightly alkaline. The minerals it picked up underground give it natural buffering capacity that purified or distilled water lacks entirely.
Does Sparkling Mineral Water Harm Your Teeth?
This is the concern most people have when they hear “acidic water.” Tooth enamel begins to soften when exposed to acids, and sparkling water’s pH of 3.5 to 6 sits in a range that could theoretically cause erosion. In practice, the risk is minimal. The American Dental Association has stated that sparkling water is far better for your teeth than sugary drinks.
The real trouble starts when sparkling water has added sugar or citric acid flavoring. At that point, it’s no longer just sparkling water. It’s a sugar-sweetened beverage that can contribute to cavities. Plain sparkling mineral water, without added flavors or sweeteners, poses very little risk to enamel with normal consumption.
Effects on Digestion and Acid Reflux
If you’re dealing with acid reflux, the pH of your water choice can make a small but real difference. Alkaline water (pH 8 or above) has been shown to deactivate pepsin, a digestive enzyme that causes the burning and tissue damage in laryngopharyngeal reflux. Some researchers have described alkaline water as a nonmedical “antacid” for this reason.
Sparkling mineral water could go either way. The carbonation itself can cause bloating and increase pressure in the stomach, which may worsen reflux symptoms in some people. But the minerals in sparkling mineral water provide some buffering that plain carbonated water doesn’t. If reflux is a concern, still mineral water with a pH above 8, like Evamor (pH 8.8) or Icelandic (pH 8.4), is the safer bet.
Mineral Water and Bone Health
One lesser-known benefit of alkaline mineral water involves bone density. A controlled study of 30 women found that drinking 1.5 liters per day of bicarbonate-rich mineral water reduced markers of bone breakdown, even in women who were already getting enough calcium. The bicarbonate content appeared to be the key factor. Water that was high in calcium but low in bicarbonate didn’t produce the same effect.
This matters because your body sometimes pulls calcium from bones to neutralize excess acid in the blood. Bicarbonate-rich mineral water supports your body’s natural buffering system, potentially reducing the need for that calcium withdrawal. The effect won’t replace medical treatment for osteoporosis, but it suggests that the type of mineral water you drink has consequences beyond simple hydration.
How to Check Your Mineral Water’s pH
Bottled water labels don’t always list the pH. Some brands include it on the label or their website, but the FDA doesn’t require a specific pH range to be printed. If you want to know for sure, inexpensive pH test strips are available at most pharmacies and will give you a reading in seconds.
As a general rule: if the water is still and sourced from a natural spring or mineral deposit, it will almost certainly be neutral to alkaline. If it’s carbonated, expect a pH between 3.5 and 6. And if it’s purified or distilled with no added minerals, it will likely drift slightly acidic, in the 5 to 6.5 range, simply because it lacks the mineral content to maintain a neutral pH.