Any rain that falls on roofs or collects on paved areas like driveways, roads or footpaths is called stormwater. The stormwater drainage system is separate from the sewage system.

All the pipes and drains inside buildings are connected to the sewer, or to a septic tank in un-sewered areas. All the outside drains except the gully trap (i.e. sewage overflow pipe) are connected to the stormwater system. The sewer takes wastewater to treatment works before being piped to the sea or irrigated over land.

The stormwater system runs from outdoor drains down the gutters and untreated into our naturally waterways (creeks, rivers, groundwaters, wetlands and the ocean). This is why only clean rainfall run-off should enter the stormwater system.

Stormwater pollution

As stormwater travels over land, it picks up all kinds of chemicals and sediments that are not naturally found in our waterways. Some of these are poisonous, even in small amounts. Others, such as nutrients, are not poisonous but may be produced in such great quantities that natural systems simply can’t cope. They can eventually cause toxic algal blooms and other pollution problems in our waterways.

The main pollutants

Stormwater pollution can be divided into three categories:

• Natural – organic material such as leaves, grass clippings and sediment
• Chemical – such as detergents, coolant, oil, grease, fertiliser and paint
• Litter – such as plastic bags and cigarette butts.

What can you do?

Every person, business, industry and government agency has an obligation to protect water quality and prevent stormwater pollution. To this end, the State Government has recently introduced a Water Quality Policy that encourages the re-use of stormwater and includes fines for people who deliberately or accidentally pollute it.

There are many things you can do to play your part and stop stormwater pollution.

More Information
What is stormwater pollution
Stormwater Management Fact Sheets (Scroll to Stormwater Management Series)
Stormwater Fact Sheets
Stormwater Pollution Prevention Project