Onsite Detention Tanks


Innovative water saving solutions

As part of The Martins Group, SWT Onsite Detention Tanks manufacture onsite detention (OSD) tanks and detention control pits (DCP). All OSD tanks and DCPs are produced on an individual basis according to your specific requirements.


osdOSD tanks control the flow of storm water from the roof to the local storm water system. Buildings with large roof surface areas capture a large volume of rainwater that may overwhelm the local storm water drainage system if allowed to flow freely. OSD tanks detain the water and provide a controlled release to prevent storm water surges.


Many council approvals for large buildings require the installation of OSD or DCP systems. However, they can only be designed by a suitably qualified hydraulic engineer. Often it is left to the plumber to interpret the engineer’s design and build an OSD system from stormwater components such as pits and water tanks. To do this on site can be tedious and often not cost effective.

SWT Onsite Detention Tanks will take your hydraulic drawings and construct a stormwater management system to suit your engineer’s design. The system can include an OSD tank and DCP complete with orifice plates, trash screens and with inlets and overflows in the correct position. Sometimes the OSD can be combined with the rainwater reuse tank to save cost. The delivery truck will crane the tank(s) and DCP into position. Once on site the system is ready to connect immediately. SWT Onsite Detention Tanks provides clear installation drawings to ensure your stormwater system is installed properly.


  Save time and money by having the tank and pits arrive on site with:

•    All inlets and outlets in position – solvent weld joints
•    Orifice plates secured and sealed in place at the specified level
•    Access rungs bonded into position
•    Pit sumps sparged

Site preparation consists of ensuring the site is excavated to the levels shown on the drawing ready to lift the tanks into position from a SWT Onsite Detention Tank crane truck.


pdfClick here to see an example of our storm water management projects.


Our trash screens help to keep water clean

One of the key features of a SWT Onsite Detention Tank is the trash screen that comes fitted to your tank. These trash screens are also fitted to our stormwater pits. Trash screens are required to be fitted to stormwater management systems where they connect to the local council water system.

Trash screen


Trash screens prevent rubbish that falls into the OSD tank or stormwater pit from being washed into the drains and into our waterways. It helps to ensure that water is kept clean and free from rubbish and debris during a storm or heavy downpour.


Our trash screens are available in two sizes:


Small trash screen
Height – 350mm
Length – 250mm
Width – 400mm


Large trash screen:
Height – 600mm
Length – 275mm
Width – 500mm


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