Hydro-Brake® Drop is a self-activating conveyance and flow control system that enables engineers to safely convey water or sewage from height while protecting infrastructure from damage, vibration, odor and noise.

Using the same advanced vortex technology that enables the Hydro-Brake® Optimum to deliver precision flow control, Hydro-Brake® Drop's vortex technology dissipates the energy of dropping water, enabling engineers to drop water from heights of up to 330 ft while preventing the damage and nuisance effects that conveying water from these heights would otherwise cause when using a conventional solution such as a drop manhole or equivalent drop shaft structure. 


  • Flood control
  • Sanitary and combined sewer (CSO) systems
  • Stormwater conveyance
  • Deep tunnel drainage and sewerage systems
  • Industrial water conveyance

Only Hydro-Brake® Drop:

  • Enables you to convey water safely through vertical drops of up to 330 ft
  • Incorporates an air switch to manage flow and control odor and corrosive gases such as hydrogen sulfide
  • Leverages our unrivaled legacy of vortex flow control expertise

You can watch a brief video that demonstrates the Hydro-Brake® Drop here.  Download the Hydro-Brake® Drop brochure here

Designed for

High flow


Drop large amounts of water safely

With Hydro-Brake® Drop flows of up to 10,500 cu ft / min can be transferred safely through drop heights of up to 330 ft. The use of multiple pipes can accommodate even higher flow rates.

Minimize erosion damage

Hydro-Brake® Drop has been designed using the latest computational fluid dynamics to minimize erosion and other kinetic damage to expensive or important structures. Rigorous real-world testing has confirmed that the destructive forces associated with cavitation and water hammer have been eliminated. 

Control odor and corrosion

Hydro-Brake® Drop incorporates a specially designed air switch that draws air through the pipe continuously as water flows through the system. This entrains air in the water, oxidizing odorous gases such as hydrogen sulfide and preventing the release of noxious gases that could otherwise cause odor and corrosion problems.

Install and retrofit easily and cost effectively

Hydro-Brake® Drop is a self-activating conveyance and flow control system with no moving parts and no requirement to keep an air core within the drop pipes, so it can be installed easily and cheaply either as part of a new construction project or as a retrofit to an existing system. Its integrated access and small pipe sizes minimize excavation costs, shaft diameters and the need for a separate access shaft. The system also benefits from a compact and simple-to-construct inlet chamber with no complicated curves or benching required.

How it works

How it works

Air Entrainment mode

At low flow water passes through the inlet pipe and drops as a film, maintaining contact with the inside surface of the Drop Pipe. This results in the formation of a central air core through the pipe. Water then enters the top of the Energy Dissipation Unit and exits the system through the sides into the bottom of the drop chamber. A weir at the bottom of the chamber creates a stilling area to absorb the release of energy from the water exiting the Energy Dissipation Unit - this ensures a smooth operation with minimal turbulence.

At increased flows, the water level in the inlet chamber submerges the inlet pipe. At this stage, air is fed in via the Air Switch, maintaining the stability of the air core and a smooth flow regime.

Pipe Full mode

If the flow rate continues to increase then the water in the upstream inlet chamber rises until it reaches the Air Switch, whereupon the system begins to enter the transition to Pipe Full mode. At this stage any increase in flow has a much lower impact on the upstream water level due to the high flow capacity. The Air Switch is designed to smoothly and efficiently regulate the transition phase, eliminating any 'glugging' or vibrations, until Pipe Full mode is reached completely and there is no more air flow through the system.

The Energy Dissipation Unit

During Air Entrainment mode air is carried down the shaft and released in the outlet chamber to ensure that damaging water hammer cannot occur. During Pipe Full mode no air is carried and therefore the drop pipe can operate at full capacity, pulling water from the inlet chamber until once again air is introduced.


Technical information

Technical information

Performance characteristics

Maximum flow: 10,500 cu ft / min (in a single unit)

Maximum drop height: 330 ft


The system is constructed from stainless steel. 

Key Components

Air switch

Controls the amount of air entering into the falling flow from the Drop Pipe, eliminating 'glugging' and therefore the damaging effects of water hammer or hydraulic shock.

Top bend

Safely transitions the flow into the vertical section of the pipe. A taper may be required depending on site circumstances.

Drop structure

A full-depth chamber housing the Drop Pipe, a control weir, maintenance access and the Outlet Structure.

Energy Dissipation Unit

Developed using the latest vortex flow control techniques, this component is designed to disperse the energy created by the falling water, in addition to effectively preventing erosion and controlling the onward flow.



Case Studies

Case Studies