<prompt> Which one of the following is the level of residual free chlorine recommended for swimming pool water disinfection?0.5 mglitre0.8 mglitre1 mglitre5 mglitre  <response>: Chlorination is the most widely used method of pool disinfection. Various workers have stated that continuous maintenance of 1mglitre1ppm of free residual chlorine provides adequate protection against bacterial and viral agents. Parks Textbook of Preventive and Social Medicine, 25th edition, Page No. 788 