Operational performance of siphonic roof drainage systems

Siphonic roof drainage systems have been in existence for approximately 30 years, and are becoming an increasingly common element of urban drainage infrastructure. In that time, only limited data have been published relating to their performance, and what does exist relates to laboratory test facilities. This text focuses on the analysis of a large data set obtained from installed siphonic roof drainage systems. Particular attention is given to the ability of the studied systems to prime and meet self-cleansing criteria during sub-design criteria events with return periods of less than one year. Conclusions are drawn regarding the performance characteristics of multi-outlet siphonic roof drainage systems, and plans for future work are outlined.