The Basics of Water pH
pH is a scale used to measure how acidic or basic (alkaline) a substance is. The scale ranges from 0 to 14, with a pH of 7 considered neutral. A reading below 7 indicates acidity, while a reading above 7 indicates alkalinity. This scale is logarithmic, meaning each whole number represents a tenfold change in acidity or alkalinity. For example, water with a pH of 6 is ten times more acidic than water with a pH of 7. While pure water is perfectly neutral with a pH of 7, the presence of minerals, chemicals, or other elements can cause its pH to fluctuate.
What water is too acidic for drinking?
For drinking water, the primary concern with a low pH is not the low acidity itself but its corrosive effects. The EPA sets a secondary drinking water standard for pH between 6.5 and 8.5, not because pH outside this range is inherently toxic but because it is considered an 'aesthetic' quality that can cause other issues. Water with a pH below 6.5 is considered too acidic because it can start to dissolve or corrode metal pipes, including copper and old lead pipes. The most significant health risk comes from the toxic heavy metals that can leach into the water as the plumbing corrodes.
Health risks associated with acidic water
Drinking water that is corrosive due to low pH can have serious health implications stemming from heavy metal contamination.
- Heavy metal toxicity: As acidic water corrodes pipes, it can pick up harmful elements like lead, copper, and zinc. Chronic exposure to lead can cause developmental delays in children and organ damage in adults. Excessive copper intake can lead to gastrointestinal issues, liver, or kidney damage.
- Dental erosion: Regular consumption of very acidic beverages (pH of 4.5 or less) can slowly wear away tooth enamel, increasing the risk of cavities and decay.
- Gastrointestinal issues: Drinking acidic water may cause or worsen symptoms like heartburn, acid reflux, and stomach pain. It could also lead to digestive issues and nutrient malabsorption.
- Skin and hair irritation: Using acidic water for washing can strip the skin of its natural oils, leading to dryness, redness, and itching. It can also leave hair feeling dry and brittle.
Causes and identification of acidic water
Acidic water can be caused by several factors, both natural and man-made:
- Natural Causes:
- Dissolved carbon dioxide: Rainwater absorbs carbon dioxide from the atmosphere, creating weak carbonic acid with an average pH of around 5.6. If this rain falls in areas with mineral-poor soil or bedrock (like granite), the water remains acidic as it enters groundwater.
- Decaying organic matter: Decomposing plant and soil materials can produce organic acids that lower the water's pH.
- Geology: The absence of neutralizing minerals, such as limestone, in rock formations allows water to remain acidic.
- Human-Induced Causes:
- Acid rain: Industrial pollutants like sulfur dioxide and nitrogen oxides dissolve in rainwater, significantly increasing its acidity.
- Mine drainage: Acidic water runoff from active or abandoned mines can contain high concentrations of heavy metals and significantly lower the pH of surrounding water sources.
- Chemical runoff: Agricultural and industrial chemicals can contaminate water supplies and alter pH.
How to identify acidic water at home
Several signs can indicate that your water is acidic:
- Metallic or sour taste: A distinctly metallic, sour, or tangy taste can result from dissolved metals in your water.
- Blue-green stains: The most common sign is blue or green stains around drains, sinks, or fixtures, which indicate copper pipes are being corroded.
- Pinhole leaks: Over time, corrosive acidic water can eat away at metal pipes, creating small pinhole leaks that can lead to significant water damage.
- Rust-colored water or stains: If you have galvanized steel or iron pipes, acidic water may produce red or reddish-brown water and stains.
- Appliance damage: Water heaters and other water-using appliances can experience premature failure due to corrosion of their internal metal components.
Solutions for neutralizing acidic water
If testing confirms your water is too acidic, several treatment options are available. The best method depends on your water's specific pH level and whether you're on a public or private water supply.
- For moderately acidic water (pH > 6.0):
- Acid neutralizer filter: A whole-house filter system filled with neutralizing media like calcite (calcium carbonate) or magnesium oxide is often used. As the water passes through the tank, the media dissolves, raising the pH. This process naturally adds minerals, which can increase water hardness.
- For very acidic water (pH < 6.0):
- Chemical injection system: A chemical feed pump injects a solution of soda ash (sodium carbonate) or caustic soda into the water line to adjust the pH. This method is more effective for very low pH levels and does not significantly increase water hardness.
- At-home water testing: For a simple check, home test kits using digital meters or test strips are widely available. For a more comprehensive analysis, especially if you have a private well, a certified lab test is recommended to detect any heavy metals.
Comparison of acidic vs. alkaline water effects
| Feature | Acidic Water (pH < 7) | Alkaline Water (pH > 7) |
|---|---|---|
| Taste | Metallic, sour, or tangy | Often described as bitter or soapy |
| Plumbing Impact | Corrosive to metal pipes, causing pinhole leaks and appliance damage | Can cause mineral scale buildup in pipes and appliances, reducing water flow |
| Stains | Blue-green on fixtures from copper pipes; rust-colored from iron | Can leave white mineral scale on fixtures |
| Contaminant Risk | Increased risk of heavy metals leaching from corroded pipes | Generally lower risk of metal leaching, but contaminants depend on source |
| Body's pH Impact | The body's internal pH is tightly regulated and not significantly affected by water pH | The body's internal pH is tightly regulated and not significantly affected by water pH |
Conclusion: Ensuring water safety
While the human body possesses powerful mechanisms to regulate its internal pH, the true danger of overly acidic drinking water lies not in its pH but in its corrosive nature. By dissolving metal pipes and releasing harmful heavy metals, acidic water poses significant health risks from contamination. Recognizing the tell-tale signs, from metallic taste to blue-green stains, is the first step toward safeguarding your health and preserving your home's plumbing. Routine water testing, especially for those with private wells, is a proactive measure to detect and address low pH issues before they cause costly damage. Depending on the severity, effective solutions range from simple filter systems using neutralizing media to more robust chemical injection methods. Maintaining your water quality is a vital aspect of nutrition and overall wellness, and ensuring a balanced pH is a key part of that process. To learn more about drinking water quality standards, you can visit the U.S. Environmental Protection Agency website.
