If you are living in an area that is constantly being developed or re-developed, chances are you deal with street floods whenever there’s a storm or heavy rainfall. The reason for this is that urban development increases “hard surface” which doesn’t absorb water, unlike soil and grass. Examples of hard surfaces are concrete paths, roofs and paved areas.

Intense rainfall dumps large amounts of water on your property. And since stormwater is no longer being absorbed into the land, there is increased run-off into local stormwater systems. As more dwellings are built, the public infrastructure becomes considerably undersized.

A good solution to ease the pressure on existing infrastructure is installing detention tanks. In fact, this is now a mandatory requirement for new homes as well as extensions. Having a detention tank plumbed into your existing drainage system is also encouraged as it makes stormwater run-off more manageable.

What is a detention tank?

A detention tank stores water collected from your hard surfaces during a rainfall event, then releases the water into the public drains at a slow, controlled rate. The slow release of the stormwater reduces peak stormwater flows and, in turn, reduces the impact on stormwater systems as well as the chance of flooding.

Detention tanks are different from rainwater retention tanks. A retention tank is a normal water tank which simply harvests rainwater and “retains” it for domestic use. Most retention tanks can only hold so much water. In case of intense rainfall, they can quickly fill up and the water overflows into the local drains in an uncontrolled manner.

On the other hand, a detention tank is intended to remain empty to make space for stormwater runoff during periods of rainfall.

It should also be noted that stormwater is different from rainwater.

Rainwater refers to rain that falls on roofs, while stormwater refers to rain that falls on hardstand surfaces other than roofs. The distinction lies in the quality of the water. Research has proven that although rainwater harvested from a roof may contain dust or debris, the debris is likely to be organic and the quality of the water makes it excellent for use in the household. Meanwhile, stormwater may have potential contaminants such as oil drops, pet droppings and rubbish.

Detention tanks may be installed above or underground.

Detention tank solutions

A detention tank is designed to empty the required amount of water at the required rate.

How big your detention tank should be depends on the specifications required by your local council. The council will also specify the size of the orifice and the flow rate of water from your detention tank. In most cases, a certain percentage of your roof or ground area will be specified for use in harvesting stormwater.

Aside from the specified size and capacity, these are the things to consider when selecting a detention tank for your property:

• Space and budget considerations
• Aesthetics
• Ease of installation
• Maintenance

If you need help choosing the right type of detention tank, contact us on 0800 768 284 and we’ll talk you through the specification and building process.