Retention and Detention Tanks
When councils require controlled stormwater release, Polymaster’s retention and detention tanks provide a certified, cost-effective solution available from 200L to 50,000L and configurable to meet local government specifications Australia-wide.
Retention and detention tanks are increasingly specified on residential and commercial developments as councils look to reduce flash flooding by controlling the rate at which rainwater enters the stormwater system.
All Polymaster above-ground round and slimline tanks can be modified to meet your council’s retention or detention requirements, and are available through more than 1,600 agricultural and plumbing stores across Victoria, South Australia, New South Wales, and South East Queensland.
ANY POLYMASTER TANK CAN WORK FOR YOUR APPLICATION
Any Tank Can Be Configured for Retention or Detention Use
There is no dedicated “retention tank” or “detention tank” product line. Any Polymaster above-ground tank, whether round or slimline, can be configured for retention or detention applications depending on your required capacity, available footprint, and council specification.
The right tank for your project is determined by those requirements, not by a fixed product category. Browse the full round tank and slimline tank ranges to find the capacity and profile that suits your site.
All tanks are available in 17 Colourbond style colours so your tank can be matched to your home’s exterior, roof, or cladding for a considered finish. Request a colour sample from your local distributor before ordering.
Not sure which configuration is right for your development? Our team can help you match the right tank capacity and retention/detention setup to your council requirements. Call us on 1800 062 064 or use the instant quote link above.
FEATURE POINTS / HIGHEST QUALITY AND STANDARDS
Highest Quality and Standards
Every Polymaster retention and detention tank is independently certified, manufactured from food-grade polyethylene, and configurable to meet council stormwater specifications so you can have complete confidence in what you are installing.
Food Grade Polyethylene
Certified to AS/NZS 4020, the Australian standard for products in contact with drinking water.
Australian Made
Designed, engineered, and manufactured in Australia – built for our climate, our conditions, and our standards.
ISO 9001 Quality Management
Polymaster holds ISO 9001 certification, the international standard for quality management systems.
Certified to AS/NZS 4766
Independently Certified to AS/NZS 4766:2020 for polyethylene storage tanks.
RETENTION VS DETENTION TANKS
What Is the Difference Between a Retention Tank and a Detention Tank?
The terms are often used interchangeably, but retention and detention refer to two distinct stormwater management functions, and councils may specify one or both depending on your development.
Detention Tanks
A detention tank temporarily holds stormwater during a heavy rainfall event and releases it slowly into the stormwater system through a small controlled outlet fitted in the side wall of the tank.
The tank is not intended to store water permanently; it fills during a downpour and empties gradually over time, ensuring it has available capacity before the next rain event.
This takes the pressure off municipal drains by reducing the peak flow rate into the stormwater network.
Retention Tanks
A retention tank stores the water collected from your roof for reuse for garden irrigation, toilet flushing, laundry, or other household uses.
By retaining water on-site rather than releasing it immediately to the stormwater system, retention tanks reduce runoff volume and provide a usable water supply.
Many councils specify a minimum retention volume on new developments as part of BASIX or local stormwater management requirements.
Combined Retention / Detention Systems
Some council specifications require a combined system, a tank that retains a base volume of water for reuse while also providing an upper detention zone that temporarily holds excess stormwater before releasing it at a controlled rate.
Polymaster’s team can configure tanks to meet combined retention/detention specifications.
Contact us with your council requirements, and we will advise on the right configuration.
HOW RETENTION AND DETENTION TANKS WORK
Taking the Pressure Off Your Stormwater System
During heavy rainfall, every roof in a catchment area simultaneously sheds water into downpipes and out through the stormwater system. When this happens across an entire suburb at once, the volume hitting the drains causes them to back up, leading to flash flooding and overloaded waterways.
Retention and detention tanks address this by intercepting the water at the source. When it rains, instead of flowing directly to the stormwater drain, water is collected in the tank first. A controlled-release fitting installed in the side wall of the tank and connected to the stormwater line releases the stored water slowly over time, at a rate the drainage system can handle. By the time the next rain event arrives, the tank has emptied to its designed level and is ready to collect again.
The flexibility of Polymaster’s system is a key advantage for builders and developers. Any Polymaster above-ground round or slimline tank can be adapted to meet retention or detention requirements, which means you are not locked into a single product or capacity. Whether you need a 200L system for a small residential lot or a 50,000L solution for a large civil development, Polymaster’s team will configure the right tank to your council’s specifications.
FEATURE POINTS
Why Choose Polymaster Retention and Detention Tanks
Configurable to Council Specifications
Polymaster’s team fits your tank to meet your specific council requirements, controlled release fittings, detention volumes, and release rates, so your development complies without the guesswork.
One-Piece Poly Construction
No joins, no seams, no part lines. Manufactured in a single piece for maximum structural strength and long-term leak resistance, important for tanks that may sit partly full for extended periods.
Double Strength UV+ Resin
Manufactured with double-strength UV+ resin for ultimate protection against the harsh Australian sun across a long design life.
Full Range - 200L to 50,000L
Available across the full Polymaster round and slimline range from 200L to 50,000L, which means the right capacity is available for any residential, civil, or commercial development requirement
DELIVERY AND DISTRIBUTION
Delivery Across Victoria, South Australia, New South Wales, and Queensland
Preparing Your Site
Truck and trailer clearance required is 19 metres long, 5 metres high, and 3.5 metres wide. Check for low branches or powerlines on your access route and ensure your gate and entrance can accommodate a 19m truck and trailer. A flat, clear area of at least 5 metres by 5 metres is required for unloading. Our logistics team will contact you approximately seven days before delivery to confirm your address and access requirements.
MORE WATER TANK SOLUTIONS FROM POLYMASTER
Explore Our Full Range of Water Tank Solutions
Our retention and detention range is one part of what Polymaster offers. If you need above-ground rainwater storage, underground systems, or slimline tanks for tight urban blocks, we have you covered.
Round Water Tanks
Available from 200L to 50,000L, Polymaster’s round poly water tanks are the most versatile above-ground storage solution for rural, residential, and industrial applications across Australia.
View Range
Underground Water Tanks
For properties where above-ground storage is not an option, our underground range offers 3,300L and 5,000L capacity completely out of sight, with the smallest environmental footprint in the industry.
View Range
Slimline Water Tanks
For narrow side yards, under-deck spaces, and tight urban blocks, our slimline range delivers serious capacity without taking up serious space available in 22 Colourbond style colours.
View Range
FAQs
Frequently Asked Questions
Everything you need to know about Polymaster’s retention and detention tank range, from how they work through to council compliance and installation.
What is a retention and detention tank?
A retention and detention tank is a rainwater tank that has been configured to control the rate at which water is released into the stormwater system. Detention tanks temporarily hold stormwater during heavy rainfall and release it slowly through a controlled outlet fitted in the side wall of the tank. The tank is not intended to store water permanently. It fills during a downpour and empties gradually over time, ensuring it has available capacity before the next rain event. This takes the pressure off municipal drains by reducing the peak flow rate into the stormwater network. All Polymaster above-ground round and slimline tanks can be modified to meet retention and detention requirements.
Why do councils require retention and detention tanks?
What is the difference between retention and detention?
Can any Polymaster tank be used as a retention or detention tank?
Yes. All Polymaster above-ground round and slimline tanks can be adapted to meet retention or detention requirements. The modification involves fitting a controlled-release outlet at the specified height in the side wall of the tank, connected to the stormwater line. Polymaster’s team can fit your tank to meet your council’s specific requirements. Contact us with your council specifications and we will advise on the right configuration and capacity.
What size retention or detention tank do I need?
The required capacity is determined by your council’s stormwater management specifications for your development, typically based on your roof catchment area, the local rainfall intensity, and the required detention volume or release rate. Your hydraulic engineer or plumber will specify the required volume as part of your development approval conditions. Polymaster’s range covers 200L to 50,000L, so the right capacity is available for most residential and commercial requirements. Contact our team with your specifications, and we will confirm the right tank for your project.
Are Polymaster retention and detention tanks certified to Australian Standards?
Yes. All Polymaster tanks are certified to AS/NZS 4766:2006 for polyethylene storage tanks and manufactured from food-grade polyethylene certified to AS/NZS 4020:2018. Polymaster holds ISO 9001 certification for quality management. These certifications are typically required by councils and certifiers when specifying retention and detention tanks on development approvals.
Need a Tank Configured to Your Council Specifications?
Talk to our team. We work with builders, developers, and hydraulic engineers to configure the right retention and detention solution for your development approval, whatever your council requires.
