Which of the following is not true about water quality estimation -: (A) Chlostridium spores indicate recent contamination, (B) Not more than 5% samples should have coliforms, (C) Sodium thiosulfate added to neutralize chlorine, (D) Coliforms must not be detected in 100 ml sample
Answer is A. Spores of Clostridium are capable of surviving in water for a longer time than the coliform group of organisms. The presence of Clostridium spores in the absence of coliform group suggest faecal contamination occurred at some remote time. Park's Textbook of Preventive and Social Medicine, 25th edition, Page No. 781