The ratio of maximum sewage flow to average sewage flow for mains up to 1 m in diameter, is___________________? August 15, 2021January 22, 2019 by admin The ratio of maximum sewage flow to average sewage flow for mains up to 1 m in diameter, is___________________? A. 1.5B. 2.0 C. 3.0 D. 4.0