What is a Storm Water Tank?

What is a Storm Water Tank?

A storm water tank, sometimes also called a detention tank or an onsite detention tank (OSD), is a big container that collects and detains storm water (rainwater) that runs off streets, lawns and other sites.

OSD tanks are used typically, as part of an effective drainage system that could help in managing the flow of storm water runoff, entering the bodies of water. Run offs can create environmental problems, especially when it is fast moving. Stream banks can erode and damage miles and miles of homes and environment of aquatic animals and plants. Run offs can also cause massive flooding issues.

An OSD tank is designed to “detain” water; that is, it holds the water for a short time only. The tank is intended to cause the water to run out, leaving the tank empty, until there is rainfall again and a short time thereafter. To prevent sudden surges of runoffs, the OSD tank has a large inlet pipe and a smaller outlet that averages the out peak flow. All our pre-cast concrete tanks have pre-set sizes and volumes.

The biggest advantage of onsite detention tank is the assistance it provides, to the local areas’ storm water drainage facilities, by draining manageable amount of water run-off, when the downpour is heavy. It is not feasible, to increase the capacity of the current drainage facilities, to keep up with the heavy flows, due to cost and space constraints. This is a reason why most councils; pass on the responsibility for the runoff, to the new homeowners.

Simply put, your local council should determine whether or not you need an onsite detention tank and to what extent you need it. Basically, the size of the tank, depends on certain factors, such as the size of your property, the surface area of your roof and the structures, within your property.

An OSD is an independent structure that is meant to function alone or it can work as a retention/detention system. It can also be used in parallel; to a retention tank, which can quickly fill up, during the rainy season. In this case, the addition of a retention tank will provide more space for the water to be detained, when it pours continuously or repeatedly. You will need to submit the proposed system to be designed to your local council for approval.


With this type of system in place, the drainage system in general; can cater to storms of higher intensity, brought about by the change in climate.

If you’re building a new home in a particular region in Australia, where on-site detention tanks are required, it’s helpful to know that Rain Cycle can design, manufacture and install your required stormwater tank. We produce pre-cast tanks of set sizes, volumes, and shapes that will be appropriate for your property. Our tanks are made of pre-cast concrete, with set sizes and volumes. They are designed either for ground level or underground installation.

If you need further information about our concrete water tanks or want to contact us for a fast quote, please call us at 1800 006 176 or visit us at www.raincycle.com.au.

We cover all Sydney suburbs, as well as the regions of Laguna, North and Mid North Coast, Southern Highlands, Bateman’s Bay, Nowra, South Coast, Mallacoota, Narooma, Balmoral, Riverina, Cobargo, Avondale, Glenmore, Glenn Ines, Mogo, Torrumbarry, Albury, Faulconbridge, Targao, Sherbrooke, Stratdickie, Maraylya, Little Hartley, Linden, Cattail, Blue Mountains and Hawkesbury, Bowen Mountains, Snowy Mountains, Murwillumbah, Kyogle, Bryon Bay, Lismore, Evan Heads. Yamba, Grafton, and the surrounding areas.