Sewer Flow Controller Sewer Flow Regulator


Patented, Proven, Low Cost, Low Embodied Carbon for Storm Water, Sewer Flooding & Pollution Reduction. This Retrofit Smart Networks Solution Help Optimise Sewer Capacity, Reduce Sewer Flooding, CSO Operations and Reducing the Volume of Plastics Entering our Oceans using a Wastewater Flow Regulator – as a Sewer Flow Regulator. It also can be used to reduce FFF (First Foul Flush) and to act as a Controlled Flusher.

The History

The inspiration for the Wastewater Flow Regulator GB Patent 2574173, also known as SFR (Sewer flow regulator) or SRU (Sewer regulator unit) by those who have come to know it, arose from a challenge set by a UK wastewater utility to find a simple means of retrofitting flow control to the outflow of a new housing development that if left unabated could increase the risk of downstream sewer flooding during heavy rainfall event.

The RDN team’s design is now highly versatile design, applicable to not only to new builds, but also capable of retrofit to existing networks, to control flows and thereby has the potential to reduce CSO spills and sewer flooding, plus regulate flows into treatment works. It also has potential to act as a sewer flusher and has since its launch landed a string of top industry awards.

To date there have been several installations across the UK including the one that is featured in this Spring Innovation

presentation, at South Woodham Ferrers in Essex. This was an installation which was completed during the autumn of 2019 and has been in active service ever since.

Irrespective of legal, media and political pressures, was acknowledged back then that something needed be done to reduce the incidents of CSO spills and sewer flooding, furthermore, to improve water quality. It is also beyond doubt also that there is a correlation between the presence of CSO spills and the occurrence of growing levels of plastics in our waterways and oceans.

Over the past three decades considerable investment had been made in network modelling, sewer flow monitoring and CSO EDM monitors. This has helped to illustrate the magnitude of the challenge and identify hotspots, analogous to the fitting if speedos in early automobiles.  Unsing the same analogy it is now time to fit the brakes to slow down and throttle back the flows and to reduce the flooding and pollution.

Long term, reducing flows and increasing capacity is the answer, whereas just closing off the CSO overflows would simply increase the incidents of sewer flooding. To achieve this requires the application of several techniques, including removing rainfall, tackling infiltration, increasing storage, enlarging sewers, increasing treatment works capacity, plus importantly flow regulation.  This all comes at a significant cost, estimated to lie between £350B to £600B according to the uk Government at pre 2023/24 inflation prices. .

Hence the talk of smart networks, where sensors, AI and modeling are used to improve the utilisation of the networks. However, this can only have limited impact on networks as the majority are gravity sewers, driven by rainfall and customer loading. What these networks require is retrofit interventions such as control valves, controlled orifices and their associated network smart sensors, to act as the brakes to truly unleash the full potential of smart networks.

British, Patented Technology to the Rescue, the Wastewater Flow Regulator is equally at home in a sewer or surface water drain.

This retrofit technology is the Low Carbon, Low Cost way to combat sewer network flooding and spills of plastics in the oceans via CSO overflows. First conceived in 2018 the Sewer Flow Regulator [SFR] unit is the perfect low carbon, low energy actuator for creating smart sewer and drainage networks.

The Wastewater / Sewer Flow Regulator

The Wastewater / Sewer flow regulator comprises of three key components. The body, the actuator assembly, and the controls compete with pneumatic drive.

The body is one of the principle patented features. The body is fabricated from welded stainless steel and includes a combined overflow chamber and weir adapter to which an extension pipe can be fitted to set the spill point. The body is optimised to achieve retrofitablity. Hence, they are individually customised to mate intimately simultaneously with the existing benching, invert, and rear wall of the chamber. When near 100% flow inhibit is require, to improve the fit, the base of the body can also include a benching adapter, designed to square up the top edges of the benching enabling an improved seal to be formed should the benching profile be poor.

The body also includes guides that accommodate and hold the actuator vertically. These guide slots include adequate lateral slack to enable the blade of the actuator to self-align with the centre of the invert, plus enable it to be removed for service.

The actuator blade design is also sighted in the patent. It is a unique laminated sandwich construction of HDPE, stainless steel, and gaskets. It is driven by pneumatic force delivered by two air hoses charged by a compressor located within the above ground control panel. The up and down sequence is initiated under the command of a remote sensor which could be a level transducer or smart network sensor such as one of RDN’s BDT level sensors, float switch or radar level transducer.

Sequence control is handled automatically by the control panel. The control panel can be mounted within a free-standing kiosk, mains or solar, or incorporated in an existing roadside kiosk. The controller includes a small air compressor and battery backup. It can also accommodate both local and remote-controlled radio telemetry, where the latter can link to smart sensors and/or the network operator’s telemetry or SCADA.

The controller also provides feedback concerning the state of operation of the regulator via volt-free contacts that can be readily interfaced to telemetry or SCADA.

Additional features include solar operation, solar panel integrity monitoring, local controls for testing and optionally radar level sensors to relay back the level of sewage stored behind the regulator.


The Wastewater / Sewer Flow Regulator YouTube Spring Innovation event 2024


Planning a SFR Deployment

There are two quite similar planning paths, one for new builds and the other for ameliorating existing network hotspots.  Both of which will be linked to incident report records of historic sewer flooding and/or CSO spill activity.

Step 1 – Desktop Survey

With the target hotspots identified, a desktop survey is normally used to initially identify the likely locations suitable for the installation of a SFR/s and associated smart network sensors.

With a new build, the location for the SFR will be typically at the boundary of the site, whereas with traditionally “hot spots” networks laterals need to be identified which have the potential to be partially or fully closed during peak flow periods.

Hydraulic modelers and flow data can be useful combined with network maps which identify respective network access chamber locations.

Step 2: Physical Survey

Many of the key features may not be documented, such as invert shape, benching depth and the potential location of the control kiosk, a physical survey is always essential. Equally the viability of installing a sensor/s, the location of the control kiosk and the viability of setting up a reliable radio telemetry link between the two.

During the physical survey the following type of data should be gathered from both the “pinch point” where the smart sensor is to be installed and the intended point of flow regulation.

At the “hot spot” Smart Level Sensor Location

  • Depth of chamber
  • Is the chamber liable to flooding.
  • Sensor mounting
  • Distance from Control point – viability of radiotelemetry link, how frequently are updates of level required?
  • Type of sensor – analogue level or set-point smart sensors such as Radio Data Networks BDT?

SFR / Regulator

  • Full or partial closure percentage?
  • Location – under a highway or verge etc.
  • Traffic management requirements
  • Depth of chamber
  • Access width
  • Invert size.
  • Benching Depth, profile, and quality.
  • Angle of invert relative to chamber wall.
  • Where applicable the diameter of the chamber.
  • Offset of the access chamber cover from the inlet side of the chamber
  • Need to slit highway to insert conduit for airlines.

SFR Control Kiosk

  • Mains or solar power
  • If solar power how many hours of solar charge are likely in winter.
  • Is the location safe / risk of accident or vandalism.
  • Distance from chamber containing SFR.

Telemetry / Control Path Survey

  • Radio telemetry link viability and fade margin
  • If distance is short, cabled telemetry.

Step 3: Sanity Check

Confirm data and produce and issue pre-production drawings of SRU to interested parties and other bespoke system components.

Step 4: Manufacture & Planning

Once approval is received from client commence manufacture. In parrel the installation team should make preparations for any groundworks such as making cable ducts for the air hoses to the chamber and cast concrete base for the kiosk.

Step 5: FAT

Conduct FAT with customer present in person or via video link. This includes a 100% system dry build and full test including sensors and telemetry.

Step 6: Deliver and Install

Deliver system to site for installation. The system is connected to telemetry and the smart sensors / radiotelemetry installed.

Step 7: Commission the system

The system is commissioned and handed to the client. Full source to screen telemetry tests are conducted also full fault reporting tested using simulated faults.

Step 8: Observe

With the system installed and running we recommend that the before and after hydraulic performance of the catchment is monitored and the net gains recorded.

In service proven at several locations since 2018 the regulator is compatible with a variety of Smart Network Sensors such as the Radio Data Networks BDT, which provides virtual real-time feedback of level.

Need for Sewer Flow Regulation

As the picture illustrates the issues are clear however controlling an open-loop system, i.e. the sewer networks requires a solution is can be retrofitted, has low embodied carbon, without the need for mains power and has the ability to receive local control signals

Retrofit Sewer Flow regulations

Having spent over 35-years in the Water and Wastewater sector the inventor came up with a solution to close all of the above issues plus has created a design that is truly affordable when compared to the alternative of creating new chambers, closing roads, over pumping, and all the disruption this involves.

Sewer Flow Regulator Innustration

Lightweight in construction the Wastewater Flow Regulator can be installed by hand without the need for a winch or crane, another carbon saving!

The regulator can be crafted / profiled to fit a existing sewer invert and benching and even can be retrofitted to plastic chambers.

Sewer Flow Regulator During Installtion into a Plastic Chamber on a New Housing Estate

The Patented overflow weir can be adjusted to set the spill point in the unlikely event of the regulator failing in the closed position.

Sewer Flow Regulator Networks

The controls for the Wastewater / Sewer Flow Regulator are Simple, on-off binary making the unit controllable from sensors such as the Radio Data Networks BDT, FDT and FST or alternatively directly from a telemetry system with nothing more complex than a digital output.

There is the choice of single point control  where the flow is inhibited by a single sensor or dual point control and the entire regulator and its controls can be solar powered.

Sewer Flow Regulator Control - Single Point


With dual-point control the flow can be modulated and levels controlled to prevent excess levels both up and down stream of the SFR.

The  examples below is a 225mm wastewater flow regulator installed into sewer to regulate the flow from the branch entering the chamber from the top.  Whereas the flow from the right is left unregulated.

Finally, who needs mains power. This can be a huge expense and result in months of delay, the regulator is perfect for solar operation and can be supplied with its own solar kiosk.

Solar Kiosk Example of the Wastewater Flow Regulator with its Inventor


Sales & orders

Please call your local distributor for prices on products, systems and solutions. Spares and accessories may also be purchased through our online web portal