Siphonic Drainage Systems

Terrain HydroMax™ Siphonic Drainage System
Our self-cleaning, high velocity Terrain HydroMax™ siphonic system provides an advanced roof drainage solution which can be used to drain large roof areas. Used on applications ranging from stadia to factory buildings, hospitals to shopping centres, it offers a complete and proven way of removing large volumes of rainwater from roofs in a controlled manner.

With a gravity flow drainage system, capacity is limited to one-third water, which adheres to the inner pipe wall, with a large two-thirds air core. Our HydroMax™ drainage system is different. Air is purged from the pipe so that it runs 100% full of water, enabling smaller diameter pipes to remove higher volumes of rainwater.


Designed to accommodate recent changes in storm patterns, as stipulated in BS EN 12056-3:2000. It uses the naturally induced siphonic principles to ‘suck’ the rainwater from the roof into small diameter pipes, creating a flow capacity up to ten times greater than that of an equivalent gravity-fed system.


Terrain HydroMax™ offers full compliance with BS 8490:2007 using Terrain FUZE BBA certified pipes and fittings.


We fully understand how important it is to have design freedom so our HydroMax™siphonic pipe work can be installed horizontally without a slope – giving you the freedom to decide where you want the downpipe locations to go.


This also enables a significant reduction in underground drainage, trenching, soil removal, treatment of backfill and often means no drainage is required under the building floor slab.



Terrain HydroMax™ Key Benefits:


  • Pipes run horizontally within building envelope
  • Reduces underground drainage requirements
  • Up to 45% cost saving overall
  • Exceptionally accurate design software
  • Easy routing of rainwater from roof to desired discharge location, making system an ideal partner
    for rainwater harvesting



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Literature & Technical info