The method of choice for purification of highly polluted water on a large scale is -: (A) Boiling and chlorination, (B) Chlorination only, (C) Superchlorination followed by dechlorination, (D) Ultraviolet light treatment
Answer is C. Superchlorination followed by dechlorination comprises the addition of large doses of chlorine to the water and removal of excess of chlorine after disinfection. This method is applicable to heavily polluted waters whose quality fluctuates greatly. Park's Textbook of Preventive and Social Medicine, 25th edition, Page No. 775