Social & Preventive Medicine All of the following statements about purification of water are true except A Sodium thiosulphate is used to neutralize certain contaminants B Coliforms must not be detectable in any 100 ml sample of drinking water C Presence of Clostridial spores indicates recent contamination of water D Coliforms may be detected by multiple tube method and indole production 💡 Explanation All of the following statements about purification of water are true except ✓ Correct Answer: C. Presence of Clostridial spores indicates recent contamination of water