Social & Preventive Medicine In post disaster phase, for ensuring safe water supply, it is advisable to have a Residual Chlorine Level of A 0.3 mg/ litre B 0.5 mg/ litre C 0.7 mg/ litre D 3.0 mg/ litre 💡 Explanation In post disaster phase, for ensuring safe water supply, it is advisable to have a Residual Chlorine Level of ✓ Correct Answer: C. 0.7 mg/ litre