OSD tank

OSD Tanks or Stormwater Harvesting – What’s the Real Difference?

What Are the Benefits of On Site Stormwater Detention Tanks?

On site stormwater detention tanks (OSD tanks) offer the temporary storage and controlled release of stormwater runoff which alleviates severe flooding caused by extreme storms. 

The main use of underground stormwater detention tanks is for slowing the release of stormwaters during peak times (Catch, Treat, Store, Release).

An OSD tank is becoming more and more critical for surviving the effects of climate change. Erratic weather patterns lead to drought, flooding, and bushfires, but you can help your community withstand these events with proper preparedness. 

Those who install OSD tanks help mitigate the effects of excessive stormwater, keeping dangerous flooding to a minimum and buying precious time for the floodwaters to be released back into the system. 

Not only does an OSD tank diminish flooding from becoming problematic, but it also allows the capture and harvesting of stormwater such that it can be treated and recycled for use as drinking water and to water the surrounding areas during drought. 

The Benefits of Stormwater Harvesting

Stormwater harvesting tanks offer the same benefits of OSD tanks, but now we can re-use that water time and time again, greening our cities, irrigating urban trees (reducing the heat island effect) and parklands and bringing greater health benefits to inner-city communities with increased access to exercise areas. 

The main use of underground stormwater harvesting tanks is for capturing and storing treated water for later use (Catch, Treat, Store and Reuse).

Here in Australia we really need to be capturing every drop and to convert an OSD Tank to a Stormwater Harvesting Asset, all we need to incorporate is a pumping station with disinfection, which will benefit the community for years to come, versus being something that just gets forgotten. 

We are now starting to see hybrid stormwater solutions that incorporate a combined OSD component and stormwater harvesting in one tank. This is a fantastic steppingstone solution for consultants to have the best of both worlds.

Fränkische has delivered stormwater harvesting solutions on the following projects:

  1. 1ML Edinburgh Gardens SWHS – awarded the IPWEA Excellence award in public works
  2. 1.3ML Dempster Park SWHS being called a ‘green oasis’. 
  3. 2ML Arndell Park SWHS

FRÄNKISCHE Retention & OSD Tanks

FRÄNKISCHE have been a market leader, for many years, in developing innovative green Stormwater Retention / Detention / Harvesting and Infiltration underground tank solutions, design for infrastructure application. Our Stormwater Harvesting/detention systems are completely modular and are unlimited in size and capacity as they work on an easily expandable system that can fit within practically any site constraints that are easy to maintain. 

We’ve created two main types of Geocellular Structural Void Storage Retention / Detention (OSD) tanks: 

  1. Rigofill ST 
  2. Rigofill ST-B 

The Rigofill ST and ST-B stormwater storage systems are extremely strong underground stormwater tanks that are hidden away from view and are so sturdy that trucks can drive over it and park on top of it without any idea what lays below. 

Our OSD tanks have been designed to handle loads of HGV60/ 60t (green module ST) and HGV30/ 30t (black module ST-B) per m2 with a minimum design life of 60 years.

The FRÄNKISCHE Rigofill ST is an underground Modular Geocellular Stormwater Storage System with one of the highest void ratio systems on the market at 96%. 

By installing an underground stormwater detention system, you will ensure excess runoff water can be stored without taking up any room above ground. 

With two stormwater retention system options available, the Rigofill ST and Rigofill ST-B, the FRÄNKISCHE OSD Tanks offer a reliable, versatile, maintenance-friendly 4th generation technology of underground stormwater storage tanks, which represents real advances and innovation for the Australian market.


FRÄNKISCHE is a family-owned company founded in Germany that has been innovating in the field of stormwater management for more than 25 years. 

With over 110 years in operation, more than 5,000 employees and 22 locations worldwide, we are passionate about improving the worldwide environmental landscape and combating the stormwater management problems that many face. 

Our focus in treating stormwater is to remove the very fine TSS63 particles, which means that our OSD tanks last longer as they don’t silt up with sludge and get blocked. With very small particles expunged, our systems for stormwater harvesting and treatment are more effective than anything else in the Australian market. 

Rigofill ST & Rigofill ST-B
OSD tank camera

Our state-of-the-art on site detention tanks are easy to clean should there be a small blockage over time. The OSD tank system is easily accessible and inspectable inside and allows for flushing and camera access. 

Our OSD tanks are made from recycled plastic because we genuinely care about the environment and the impact we make over the long term. 

If you want to work with the best company in stormwater drainage and urban stormwater management, then get in touch, and we’ll be happy to discuss in detail what type of OSD or Stormwater Harvesting tank system would be best for your next green infrastructure project! 


Give us a call or drop us an email to get the ball rolling.