If you are building a new home, there are a number of requirements that your local council might require you to meet. Depending on where you are located, one requirement might be for stormwater detention.
This article is the third in a series of articles exploring the topic of stormwater and the importance of stormwater detention in property development. In our previous article, we explored the differences between stormwater detention tanks and more typical water retention tanks. This article looks at why stormwater detention is important to plan for with new homes and how detention tanks can help.
Why Detain Stormwater?
During storms and a heavy downpour of rain a lot of stormwater can be generated increasing the risks of floods in urban areas. This is worsened by increasing residential densities and expanding industrial and commercial buildings that increase pressure on existing underground drainage infrastructure.
Many councils consider increasing the capacity of existing drainage to cater to increased stormwater flow as being infeasible due to space and cost constraints. Since councils are unable to reasonably deal with the issue alone, the burden of responsibility is often placed on homeowners to help make their property’s stormwater run-off more manageable.
How is Stormwater Detained?
Stormwater sensitive design can be planned for during the development of a property. There are also more natural techniques that involved maintaining existing property topography, vegetation, deep-rooted trees and minimising covering of natural ground surface with concrete surfaces.
New houses often need to have on-site detention facilities constructed as part of their home drainage system. Some include water tanks or concrete basins beneath driveways, designed to capture stormwater runoff from a residential lot and hold it a little longer to reduce the impact of flooding.
The stored water drains slowly through a small opening near the base of the tank to the stormwater system. When many properties in flood prone areas have these detention systems, the downstream flood ‘peak’ during large storms is reduced and flood damage is minimised.
Solutions for onsite stormwater detention include:
- Stormwater detention tanks: specially designed tanks that have split storage inside, one compartment for storing rainwater, the other for detaining stormwater.
- Underground storage tanks: for storing stormwater runoff, normally designed with your rainwater harvesting system to receive excess water overflowing from a rainwater tank or placed under driveways where a lot of stormwater runoff can be received.
- Rainwater tanks: while water doesn’t slowly drain away, large water storage tanks may satisfy some council requirements.
- Surface holding areas: basin, soakage pits, trenches or swimming pools.
Stormwater Detention Tanks
New houses built in areas where councils require homeowners to help with stormwater often require stormwater detention tanks to be installed. Detention means the water will be “detained” for a limited period. These tanks are intended to remain empty, except during periods of rainfall and for a short time thereafter.
Unlike normal rainwater tanks, the distinguishing feature of a stormwater detention tank is that it is specially fitted with a valve to slowly release the water over time. You have basically two options with a stormwater detention tank solution:
- use two water tanks, one to harvest rainwater and the other for stormwater detention, or
- use a specially made dual use water retention/detention system.
Stormwater detention requirements can vary from one council to the next, so it is important to consult your local council before implementing any stormwater sensitive solution.
If you are looking for stormwater retention or detention tanks for your home, talk to our team for expert advice on your property needs.