The pH scale is a fundamental measure of a substance's acidity or alkalinity, ranging from 0 to 14. A pH of 7 is considered neutral, with anything below 7 being acidic and anything above 7 being alkaline or basic. While pure water ideally has a pH of 7, the pH of bottled water can vary significantly due to its source, processing, and added minerals. For example, studies have shown that some popular bottled water brands are more acidic than others, leading to consumer questions about which water brand has the lowest pH.
Factors Contributing to Low pH in Bottled Water
Several factors can cause bottled water to be more acidic. The most common is the purification process, particularly reverse osmosis, and exposure to carbon dioxide.
The Role of Reverse Osmosis
Reverse osmosis (RO) is a filtration process that effectively removes contaminants by forcing water through a semipermeable membrane. While this produces very clean water, it also strips away naturally occurring minerals like calcium and magnesium that act as natural pH buffers. The result is demineralized water that can have a slightly acidic pH, often falling between 5.5 and 7.0. To counteract this, some RO systems include a remineralization stage, but not all do.
The Effect of Carbon Dioxide
Carbon dioxide ($CO_2$) naturally exists in the atmosphere. When purified water is exposed to air, it can absorb $CO_2$, forming a weak carbonic acid ($H_2CO_3$). This reaction causes the water's pH to drop, potentially falling as low as 5.5 in a short period. This is why even a glass of supposedly neutral purified water can become slightly acidic just by sitting out.
Added Ingredients
Some bottled water products, especially flavored or enhanced waters, contain added ingredients for taste or function. These additives can lower the water's pH, making the product more acidic than plain water. For example, many flavored fitness waters have a significantly lower pH than unflavored bottled water.
Brands with the Lowest Reported pH
Multiple independent tests of bottled water brands have revealed significant variations in pH levels. While results can differ based on testing conditions, certain brands consistently show lower pH values. According to various sources, some of the most acidic water brands include:
- Vitaminwater: Often cited with a pH around 3.4, due to its additives.
- Propel Zero/Fitness Water: These sports waters typically have pH levels in the 3.5 to 3.6 range.
- Penta: Reportedly has a pH as low as 4.0.
- Dasani: Often found to have a pH around 4.5 to 5.0, sometimes lower.
- Aquafina: Has been measured with a pH as low as 5.5.
- Voss: Sometimes reports on the lower end, around 6.0.
Comparison of Popular Water Brand pH Levels
This table provides a snapshot of pH ranges for several well-known brands, based on various test results. Note that specific values can fluctuate.
| Brand | Typical pH Range | Notes |
|---|---|---|
| Dasani | 4.5 - 5.6 | Purified via reverse osmosis with added minerals. |
| Aquafina | 5.4 - 6.0 | Purified water, low mineral content. |
| Propel Zero | ~3.5 | Enhanced fitness water with additives. |
| Vitaminwater | ~3.4 | Flavored water with additional ingredients. |
| Smartwater | ~6.5 - 7.0 | Vapor-distilled with added electrolytes. |
| Poland Spring | ~5.8 - 7.2 | Natural spring water, varies by source. |
| Evian | ~7.0 - 7.5 | Natural spring water. |
| Fiji | ~7.5 - 7.6 | Natural artesian water. |
| Essentia | ~9.0 | Ionized alkaline water. |
The Real-World Impact of Water pH on Your Health
While some fear the effects of acidic water, the human body is a highly efficient pH regulator. The stomach's natural pH is extremely low (1.5-3.5) to aid digestion, and the kidneys are experts at maintaining the body's internal acid-base balance. Therefore, for most healthy individuals, drinking moderately acidic bottled water is unlikely to pose a significant health risk.
However, there are still potential implications to consider:
- Metallic Taste: Some people are sensitive to acidic water and may find it has a metallic or sour taste.
- Corrosion of Plumbing: Consistently using low-pH water can be corrosive to metal pipes and plumbing fixtures, potentially leaching metals like lead and copper into drinking water over time. While this is a larger concern for tap water systems, it highlights a consequence of sustained low pH.
- Oral Health: Highly acidic beverages can potentially erode tooth enamel over time. While bottled water is far less acidic than soda or fruit juice, those concerned about dental health may choose neutral or alkaline options.
Conclusion: Making an Informed Choice
There is a notable difference in pH among popular bottled water brands, with processed waters like Dasani and Aquafina often registering as more acidic than naturally sourced spring waters like Fiji or Evian. The lowest pH values are typically found in flavored and enhanced water products with additives. While the human body is generally adept at managing its internal pH, making mildly acidic bottled water a non-issue for most, those with specific health concerns, particularly regarding dental health or plumbing, may prefer neutral or alkaline options. For bottled water, the key is understanding the purification method and potential additives. For home tap water, regular testing is advisable, especially in older homes with metal piping, to monitor for corrosive effects. Ultimately, the best choice depends on individual preference and specific health considerations.
For more detailed information on drinking water standards, consult the official guidelines from the U.S. Environmental Protection Agency (EPA).
