Small outlets are easy to block
A detention tank relies on a small outlet to control the rate of discharge. Debris can restrict or block this outlet, reducing the system’s ability to perform as designed.
TankGuard™ by Promax
Smarter Protection for Stormwater Detention Tanks
TankGuard™ helps protect underground and Slimline stormwater detention tanks from one of the most common causes of system failure: a blocked discharge outlet.
Using clever hydraulic design and no moving parts, it helps clear outlet blockages and restore controlled discharge when the tank is under load.
The challenge
The hidden risk inside stormwater detention systems
As New Zealand’s urban areas become more built-up, more hard surfaces are created across roofs, driveways, paving and roads. During heavy rain, these surfaces increase stormwater runoff and place greater pressure on local drainage networks.
Onsite stormwater detention helps manage this by temporarily holding runoff and releasing it slowly through a small discharge outlet. That outlet is essential to controlled discharge, but it is also one of the most vulnerable points in the system.
If the outlet becomes blocked by leaves, sediment or other debris, the tank may continue filling until it reaches the overflow. At that point, the system is no longer releasing water through the designed controlled discharge pathway.
Why protection matters
Why detention systems need protection
A detention system can only protect downstream infrastructure if the controlled discharge outlet continues to work as designed.
Maintenance is often overlooked
Underground systems are not always visible or easy to monitor. Over time, this can lead to an out of sight, out of mind problem.
Overflow is not controlled discharge
Once water reaches the overflow, the tank is no longer discharging through the controlled outlet. This can reduce the intended stormwater management benefit.
Introducing TankGuard™
TankGuard™ is designed to help protect the controlled discharge point inside a stormwater detention tank.
If the primary discharge outlet becomes blocked, TankGuard™ redirects stormwater through an internal riser and external flow path. This creates a hydraulic effect that helps dislodge the obstruction, clear the outlet and return the system to normal controlled discharge.
The result is a smarter, more resilient detention tank solution for underground and Slimline stormwater applications.
How it works
From blocked outlet to restored flow
Controlled discharge operates normally
Stormwater is detained in the tank and released through the outlet at the designed rate.
The outlet becomes restricted
If debris restricts the discharge outlet, the water level rises and the system may no longer release flow as intended.
TankGuard™ responds as water rises
When the water reaches the TankGuard™ pathway, flow is redirected through the internal riser and external pipework.
Hydraulic flow helps clear the obstruction
The redirected water creates a clearing action that helps dislodge debris at the outlet.
Normal operation can resume
Once the outlet is clear, controlled discharge can resume and the detention system can continue operating as designed.
Engineered by Promax
Clever hydraulic design, no moving parts
TankGuard™ relies on water movement and hydraulic flow principles rather than mechanical components. There are no moving parts to seize, wear out or require ongoing adjustment.
Because the system is factory-fitted by Promax, it is supplied as part of the tank system and set up to perform from day one.
Helps protect the controlled discharge outlet
Uses hydraulic flow to help clear obstructions
No moving mechanical parts
Factory-fitted by Promax
Supports long-term detention performance
Available for selected underground and Slimline detention tanks
Designed to keep water moving when it matters
TankGuard™ adds protection at the point where blockages can cause the greatest performance issue. It does not replace good stormwater design, filtration or appropriate maintenance, but it gives the detention system an extra layer of resilience.
Stormwater is capturedRunoff enters the tank and is temporarily detained during rainfall.
Controlled discharge beginsWater exits through the small outlet at the engineered discharge rate.
TankGuard™ provides an alternate flow pathIf the discharge point is blocked, rising water is redirected through the TankGuard™ pathway.
The blockage is helped clearHydraulic flow helps dislodge debris so normal controlled discharge can resume.
Why choose TankGuard™?
Practical protection for better detention performance
Helps maintain controlled discharge
Helps protect the small outlet that allows detention tanks to release stormwater at the designed rate.
Reduces outlet blockage risk
Designed to help clear debris that may otherwise restrict the discharge outlet.
Factory-fitted for confidence
Installed by Promax during manufacture, helping ensure the system is correctly configured from the start.
No moving mechanical parts
Uses hydraulic flow principles instead of mechanical parts, helping reduce system complexity.
Built for New Zealand stormwater conditions
Designed for real stormwater environments where debris, sediment and maintenance gaps can affect performance.
Developed by Promax
A Promax-developed solution available with selected Promax detention tank systems.
Product availability
Available on selected Promax tank systems
TankGuard™ is available as an add-on for selected Promax underground and Slimline stormwater detention tanks. It is factory-fitted during manufacture, so it should be specified when your tank is ordered.
TankGuard™ is not designed as a retrofit option. For detention projects that need additional blockage protection, speak to Promax early so the correct tank and configuration can be specified.
Best specified for
- Selected underground detention tanks
- Selected Slimline detention tanks
- Sites with small controlled discharge outlets
- Projects where maintenance access may be limited
For councils, engineers, developers and builders
A practical solution for better long-term system performance
Detention performance is only valuable if the system continues to operate as designed after installation. TankGuard™ helps address a known weakness in stormwater detention systems by protecting the small discharge outlet from blockage-related failure.
It gives project teams a practical way to improve system resilience while keeping the solution simple for homeowners.
Well suited to
Residential developments
Medium-density housing
Subdivisions
Urban infill projects
Onsite detention requirements
Maintenance-sensitive sites
Technical summary
Simple to specify, smart in operation
TankGuard™ is a factory-fitted stormwater detention protection system designed to help clear blockages at the discharge outlet. If the outlet becomes blocked, rising water is redirected through an internal riser and external flow path, creating a hydraulic clearing action that helps dislodge debris and restore normal controlled discharge.
Helps protect the controlled discharge outlet
Helps clear debris-related outlet blockages
Uses hydraulic flow, not moving parts
Factory-fitted by Promax
Available for selected detention tank systems
Common questions
TankGuard™ FAQs
What does TankGuard™ do?
TankGuard™ helps protect the controlled discharge outlet in selected Promax stormwater detention tanks. If the outlet becomes blocked, the system uses redirected water flow to help dislodge the blockage and restore normal operation.
Why is the discharge outlet so important?
The discharge outlet controls how quickly stormwater leaves the tank. In many detention systems this outlet is small, often around 10mm to 20mm, which makes it vulnerable to blockage from leaves, sediment and other debris.
Does TankGuard™ replace regular maintenance?
No. TankGuard™ adds an important layer of protection, but good stormwater design and preventative measures are still recommended. This may include inlet screens, gutter protection and regular checks where appropriate.
Does TankGuard™ have moving parts?
No. TankGuard™ uses hydraulic flow principles rather than moving mechanical parts.
Can TankGuard™ be retrofitted to an existing tank?
No. TankGuard™ is factory-fitted by Promax and should be specified when the tank is ordered.
Which tanks is TankGuard™ available on?
TankGuard™ is available for selected Promax underground and Slimline stormwater detention tanks. Speak to the Promax team to confirm the right configuration for your project.
Ask an expert — it's free.
Protect the long-term performance of your detention tank
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