The purpose of a flow control is to regulate the rate of discharge from a development to prevent downstream flooding by mimicking pre-development runoff rates. They are often specified as part of a SuDS solution where the site is not suitable for infiltration techniques.

Flow controls can be split into two broad categories :

  • active
  • passive

Aquality offer both active and passive surface water control systems


The advent of real time controls (RTC) with continuous monitoring adaptive control using IoT, such as ASC give us the ability to control  the rate of discharge from a development over a range of storm events and conditions, and to alter parameters remotely if  change is required.  These dynamic controls allow us to future proof  our drainage systems and to optimise their performance on a site or catchment scale , for example, it is possible to avoid wet weather discharge completely ,to limit flow to the same rate regardless of hydraulic head , to store water for re-use, or to improve water quality.

Using an active flow control device will only enhance the performance of the surface water drainage system and will not require hydraulic remodelling to comply with planning conditions.

As these controls systems are bespoke please contact us to discuss your requirements.



Passive surface water flow controls are traditionally what are used to regulate the rate of discharge from a development site, such controls can be used with any type of drainage structure, but are often used in conjunction with attenuation systems.

The purpose of the control is to limit the flow into a surface water sewer or water course  to a predetermined rate as set by the regulator (EA, Utility company etc), or to a rate that replicates greenfield runoff rates. These controls are designed to meet a specified discharge rate for a given storm event e.g. 1:100 year, it is in this sense that they are passive controls as they cannot be altered once installed.

Aquality offer bespoke orifice plates and vortex controls manufactured from 304 stainless steel complete with integral remote bypass facility. As these controls are made to order we will require the following basic information to size the control:


  • Design hydraulic head
  • Design flow rate


We also offer bespoke flow control chambers to mount our surface water controls into. These are available from 600mm – 2100mm diameter and up to 4.0m in depth

Aquality offer a full range of controls and chambers whether Orifice, Vortex, or Aqua Storm Control. As all these controls are bespoke please contact us to discuss your requirements.