What pH is Water?

The pH of water varies depending on its purity and source, but pure water is inherently neutral.

Understanding Water pH

Water's pH level indicates its acidity or alkalinity, measured on a scale from 0 to 14. A pH of 7 is considered neutral, below 7 is acidic, and above 7 is alkaline (or basic).

1. Pure Water (Distilled or Deionized)

• Exact pH: Pure water, free from dissolved minerals, gases, or other impurities, has a pH of 7.0 at 25°C (77°F). This is the definition of a neutral solution.

2. Drinking Water

• Typical Range: The pH of most drinking water is not exactly 7 due to the presence of dissolved minerals, gases, and other substances. Typically, the pH of drinking water lies within the range of 6.5 to 8.5. This range ensures the water is safe and palatable for consumption.
• Factors Influencing pH:
  • Source: Groundwater often has a higher mineral content, influencing pH. Surface water can be affected by environmental factors.
  • Treatment Processes: Water treatment can adjust pH for various reasons, such as corrosion control or disinfection effectiveness.

3. Natural Waters (Rivers, Lakes, Rain)

The pH of natural bodies of water can fluctuate significantly based on environmental conditions and geological factors.

• Variations:
  • Lower pH: Natural waters can exhibit a lower pH, for instance, due to the effects of acid rain or run-off from acidic soils.
  • Higher pH: Conversely, natural waters in areas rich in limestone or other alkaline minerals tend to have a higher pH.
• Measurement: The pH of an aqueous sample, such as natural water or drinking water, is commonly measured electrometrically using a glass electrode.

pH Scale Overview

The pH scale is logarithmic, meaning each whole number change represents a tenfold difference in acidity or alkalinity.

Maintaining an appropriate pH is crucial for environmental health, water quality, and various industrial applications.