Do You Need Stormwater Retention Tanks?

As property development continues to expand in New Zealand, the management of stormwater is becoming increasingly important. With infrastructure becoming overloaded or simply non-existent, we need to become smarter about how we manage stormwater, using alternatives with fewer impacts on our streams, rivers, and other waterways. One such alternative is the use of stormwater retention tanks.

While water tanks are a common sight in rural areas, where roof water is collected and reused in the house, they are not as widespread in urban areas. However, changes to planning documents, such as the Auckland Unitary Plan, are attempting to control new impervious surfaces and how they are managed. As a result, stormwater retention tanks are becoming more common.

So, what are stormwater retention tanks, and how do they work? These tanks collect water from roofs and other impermeable surfaces, store it, and release it at a much lower rate, holding water back during high rainfall events and releasing it slowly over a longer period through a small orifice. This reduces the impact of extra water in the local environment, reduces flooding, scouring, and erosion.

Stormwater retention tanks are often installed underground and require specific designs tailored to the site and use. They are especially important in new developments where there may be additional demands on stormwater systems that do not have the capacity to handle further loads. These tanks are designed to store rainwater from roofs, driveways, paths, and other impervious areas and discharge it to the stormwater system from the tank through a small diameter orifice pipe at a rate that the stormwater system can manage.

Detention tanks, such as the stormVAULT, are designed to remain empty except during periods of rain. When it rains, the tank collects stormwater and releases it at a rate specified by design into the council stormwater system. This helps prevent flooding on your property, reduces the impact of heavy rain on the council system, and protects our waterways and coastal environments from erosion. If the tank completely fills, there is an overflow the same size as the inlet to avoid flooding.

Due to the fact that detention tanks reduce demand on council stormwater systems and the likelihood of flooding and pollution, many new houses have on-site detention tanks constructed as part of their home stormwater system. If you are adding roof space by extending or building in areas where stormwater systems are undersized or have not been renewed, a detention tank may also be necessary. There are a variety of underground and above-ground solutions available in a wide range of sizes to suit your property and landscape.

Stormwater retention tanks are becoming an increasingly important part of property development in New Zealand, providing an effective solution for managing stormwater and reducing the impact of extra water in the local environment. As the demand for these tanks continues to increase, it is important to consult with experienced architectural designers who can provide tailored solutions specific to your site and use.

Want to hear more? 

Modal Architecture is a local architectural design firm specialising in high performance, sustainable, and lifestyle homes around New Zealand. If you want to find out more - get in touch below to discuss this article or your upcoming project.

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