Stormwater
- What is stormwater?
- What is rainwater collection?
- How do I get the permissions to harvest stormwater?
What is stormwater?
Once rain touches the ground, it is called stormwater. Stormwater can be collected (harvested) and reused for many purposes. Stormwater can become polluted from uncontrolled catchment sources. As a result, stormwater quality can vary widely and may need to be treated before it can be used. In urban areas, the best quality water is rainfall captured from roofs before it meets up with other stormwater at ground level or in drains.
The Sustainable Water Strategy for Central Region (DSE October 2006) defines urban stormwater as “The net increase in run-off and decrease in groundwater recharge resulting from the introduction of impervious surfaces such as roofs and roads within urban development”.
Urban areas have large areas of hard surfaces when compared with natural environments. Hard surfaces include roofs, roads, car parks, pathways and other paved areas. When it rains in urban areas, the amount of water that is able to soak into the ground is reduced, so more water runs into stormwater drains.
Stormwater run-off from suburban streets and hard surfaces is the biggest polluter because of what it picks up and carries into rivers and creeks. It becomes a bigger challenge the more Melbourne grows.
Stormwater can become polluted on its way to our rivers, creeks and bays by things such as:
- Atmospheric pollution
- Metals and other toxicants on roads and hard surfaces
- Pollution from ageing sewerage systems underground that can infiltrate the stormwater system
- Runoff from industrial and business sites
- Litter
- Grass clippings
- Leaves
- Oil (dripped from cars), and
- A range of other pollutants.
As a result, stormwater quality can vary widely. Stormwater quality will depend on the environment where the rain fell and how often it rains. In Melbourne, stormwater flows mainly into roadside drains, which in turn flows into larger underground drains and then into local rivers and creeks or directly into Port Phillip Bay or Western Port.
Before it can be used, stormwater may need treatment, depending on the requirements of the end use. Treatment can be in the form of natural systems such as wetlands, or mechanical water treatment plants.
What is rainwater collection?
In the urban environment, the best quality water during rainfall is captured before it becomes stormwater. This water is collected directly from roofs and stored in tanks, before it has the chance to become polluted from the ground or in the drainage system.
Rainwater collected in tanks from domestic or commercial roofs can be used for many different purposes. Rainwater collection does not require a stormwater harvesting licence from Melbourne Water.
The Queen Victoria Market’s Rainwater Harvesting Scheme is a good example of how harvested rainwater can provide a new water source. This scheme is expected to save the Queen Victoria Market more than 5 million litres of drinking water each year.
See: 2009 Stormwater Excellence Awards - Queen Victoria Market
If you would like more information about installing a rainwater tank, please contact your retail water company:
How do I get the permissions to harvest stormwater?
If you are considering developing a stormwater harvesting project or if you are well into the design phase there are certain approvals that you will require. Stormwater harvesting requires approval from Melbourne Water if:
- The connection is to any new or modified stormwater connection into a drain, watercourse or open channel controlled by Melbourne Water
- A stormwater harvesting licence is required for the quantity of stormwater.
We are currently developing our webpage to process stormwater harvesting applications and enquiries. If you require more information please see our stormwater connections page or alternatively please call 131 722.