What is pH?
pH stands for "potential of hydrogen" and is a measure of the concentration of hydrogen ions in a substance. It is measured on a logarithmic scale from 0 to 14, where 7.0 is considered neutral. A value below 7 indicates acidity, while a value above 7 indicates alkalinity. While pure water has a pH of exactly 7, natural drinking water sources rarely maintain this exact balance, with most municipal water supplies falling within a regulated range.
The Official Recommended pH Range for Drinking Water
For public water systems, organizations like the U.S. Environmental Protection Agency (EPA) recommend maintaining a drinking water pH level within the range of 6.5 to 8.5. This standard is based on secondary or aesthetic considerations, such as taste and odor, rather than primary health concerns directly related to pH itself. Water authorities aim for this range to prevent corrosive reactions in plumbing and ensure water remains palatable for consumers. The World Health Organization (WHO) also publishes guidelines that align with this general range.
The Health and Safety Implications of Imbalanced pH
The potential health risks from imbalanced water pH are largely indirect. It is less about the water's acidity or alkalinity and more about what the extreme levels cause to happen. Your body is highly efficient at maintaining a stable pH balance in your blood, and ingesting slightly acidic or alkaline water won't significantly disrupt this process.
Risks of Acidic Water (Low pH)
Water with a pH below 6.5 is considered acidic and poses several risks, primarily due to its corrosive nature.
- Leaching of Heavy Metals: Acidic water can dissolve metal ions from plumbing fixtures and pipes, potentially introducing harmful contaminants like lead, copper, and zinc into your drinking water. Chronic exposure to high levels of these metals can cause serious health issues.
- Plumbing Damage: The corrosive action of acidic water can damage pipes, fixtures, and water-using appliances, leading to costly repairs over time.
- Metallic Taste: Consumers often report a bitter or metallic taste when drinking water with a low pH.
- Potential Health Effects: Although the main risk is metal contamination, some sources suggest low pH can irritate the digestive system and affect dental health by eroding tooth enamel.
Risks of Alkaline Water (High pH)
Water with a pH above 8.5 is considered alkaline. While less corrosive than acidic water, it can also cause aesthetic and functional issues.
- Aesthetic Issues: Highly alkaline water can have an unpleasant, slippery feel and a soda-like or bitter taste. It can also leave scale deposits on fixtures and pipes.
- Limited Disinfection: Excessively alkaline water (above 8.0) can interfere with the effectiveness of chlorine disinfection in water treatment, potentially affecting microbial safety.
- Extreme High pH: Although extremely rare in typical drinking water, highly caustic water (e.g., pH above 10) can cause eye and skin irritation in animals and digestive issues in sensitive humans.
How to Measure and Adjust Your Water's pH
If you have concerns about your water's quality, testing its pH is a straightforward process. You can use relatively inexpensive home test kits or seek a more precise laboratory test.
To increase the pH of acidic water, you can install a neutralizing filter containing materials like calcite or magnesium oxide. Some people add a pinch of baking soda to a glass of water, but this is a temporary fix that increases sodium and is not recommended for regular use. To decrease the pH of alkaline water, some commercial systems or treatments are available, but consulting with a water quality professional is recommended for more controlled adjustments.
Comparison of pH Levels in Different Water Types
| Water Source | Typical pH Range | Key Considerations |
|---|---|---|
| Tap Water | 6.5–8.5 | Regulated by municipal utilities to fall within EPA guidelines for palatability and plumbing protection. |
| Bottled Water | Highly variable (5–10) | Natural mineral waters may be more alkaline (e.g., pH 8–9.5) due to dissolved minerals; purified waters are closer to neutral. |
| Alkaline Water | 8–10 | Often created through electrolysis or mineral addition; alleged health benefits lack strong scientific backing. |
| Reverse Osmosis (RO) | 5.5–7 | The filtration process removes minerals, often resulting in slightly acidic water. Modern systems may add minerals back to increase pH. |
Conclusion
Understanding what level of pH is drinkable is less about a single perfect number and more about understanding the safe range and the implications of straying outside it. The EPA's recommended range of 6.5 to 8.5 for public water is a reliable benchmark, prioritizing safety for plumbing and consumer health. While the body can easily process water within this range, levels far below 6.5 can cause serious issues by corroding pipes and leaching heavy metals. Extremely high alkaline levels, while less dangerous, can still affect taste and infrastructure. Ultimately, for everyday consumption, a balanced pH is preferable. Regular testing, especially if you get water from a private well, is the best way to ensure the quality of your water supply. More information on the science of water pH is available from the USGS.
