Drinking-water (potable water) quality standard: What should be the acceptable pH range for safe human consumption according to common water-quality guidelines (municipal supply and treated groundwater)?

Introduction:
Drinking water should neither be strongly acidic nor strongly alkaline. The pH window ensures palatability, corrosion control in the network, and effectiveness of disinfection.

Given Data / Assumptions:

• Context: Potable water standard.
• We seek the acceptable pH range that balances health and system protection.
• Room temperature conditions assumed.

Concept / Approach:
pH measures hydrogen ion activity on a 0 to 14 scale. Neutral is pH 7. Acceptable potable water is typically slightly acidic to slightly alkaline to prevent corrosion and scaling while maintaining taste and disinfectant stability.

Step-by-Step Solution:
Step 1: Note that neutral water is pH 7.Step 2: Practical distribution systems target a slightly buffered range around neutrality.Step 3: The commonly accepted range for potable water is about 6.5 to 8.0 (often cited up to 8.5).

Verification / Alternative check:
At pH below 6.5, corrosion of pipes increases; above about 8.0 to 8.5, taste issues and scaling rise and chlorine disinfection becomes less effective.

Why Other Options Are Wrong:
1.0 to 1.5: Extremely acidic and unsafe. 13.0 to 14.0: Highly caustic. 4.0 to 5.0 and 5.5 to 6.0: Corrosion risk and poor taste; not acceptable for distribution.

Common Pitfalls:
Assuming pH must be exactly 7.0. Water can be safe within a reasonable range around neutrality.

Final Answer:
6.5 to 8.0