<prompt> Minimum contact period for chlorination -30 minutes1 hour2 hours5 hour  <response>: Ans. is b i.e., 1 hour Water typeRecommendedResidual chlorine levelContact periodDrinking waterWater bodies, post disasterSwimming pool sanitation 0.5 mg per litre ppm 0.7 mg per litre ppm 1.0 mg per litre ppm1 hour1 hour1 hour 