Question

The maximum allowable concentration of fluorides in drinking water is:
1. 1.00 mg per litre
2. 1.25 mg per litre
3. 1.50 mg per litre
4. 1.75 mg per litre

Answer 1

Correct Answer - Option 3 : 1.50 mg per litre

The correct answer is 1.50 milligram per liter.

• The World Health Organization recommended the upper limit of fluoride in drinking water is 1.5 mg/l, for several countries such as Canada, China, India, Australia, and the European Union.
• Desirable fluorides in drinking water are 1 mg/l.

• The oxidation state of the fluoride ion is -1.
• WHO's Guidelines for Drinking-water Quality, set up in Geneva, 1993.
  • pH value: 6.5 to 8.5.
  • Total hardness (as CaCO₃): 300 mg/l.
  • Iron: 0.3 mg/l.
  • Chlorides: 250 mg/l.
  • Sulphate: 200 mg/l.
  • Cadmium: 0.01 mg/l.