Siphonic Roof Drainage System


Siphonic storm drainage is based on the simple principle of a siphon with negative pressure, caused by the height of the building, to pull storm water off the roof. The bigger the difference the faster the flow. Pipes are flushed at high velocity and self-clean as air exits the system. Gravity drains require 2/3 air and large pipes and Siphonic drains do not use air, pipes are sized for a 100% fill ratio, a   diameter reduced by ½. No pitch, slope, or equipment is needed. Fewer penetrations, vertical drops, trenching, civil connections, and site disturbance. Due to the lack of air, noise is reduced in full siphonic Mode, and water discharge is up to 8x velocity. Siphonic drainage reduces ponding, and clogs, and extends roof longevity.