Sewerage & drainage areas
Find maps of the metropolitan drainage districts and statewide sewerage areas, with information on how your bill is calculated.
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Drainage services
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Rain, storms, and floods are a natural Rain water is a valuable resource. We work to improve waterway health, provide opportunities to reuse rain water and prevent flooding. part of our unique lifestyle in WA, which is why it’s important we have an efficient drainage system to manage stormwater across our service areas.
Drains collect stormwater runoff from roads, driveways and other surfaces following a rain or storm event to help protect properties from flooding.
Often overshadowed by water supply and sewerage, our drainage system has played a crucial role in managing our state’s water for centuries.
History of Perth drains
The drainage system in Perth is one of the oldest parts of our operations, dating back to the 1800’s.
Perth is built on a series of shallow lakes that originally existed between the Swan River and Lake Monger, generally along the route of the current railway line and freeway.
Whilst these areas were rich in soil and ideal for market gardens, they were also highly prone to flooding – leading to the start of drainage works in 1848.
By 1875, large-scale drains were constructed – some of which still exist today.
Over the years, our drainage system continued to improve to handle ongoing floods and adapt to our growing city’s needs.
By 1913, when Metropolitan Water Supply, Sewerage and Drainage Department (now part of Water Corporation) took over Metropolitan Drainage, there were 12.5km of main drains in Perth and its surroundings.
Today, there are around 2,500km of open and piped drains across WA, managed by Water Corporation.
Our drainage system today
Across the Perth metro area, Great Southern, and parts of the South West, we manage more than 2,500km of both piped and open drains.
These drains typically provide an outfall for the entire catchment, with council/local authority drainage (like street drains and gullies) feeding into them.
When it rains some water naturally seeps into the ground, our drainage systems are designed to prevent flooding of low lying areas and convey excess stormwater from the catchment into either rivers, lakes, or the ocean. The remaining water runs into our drainage systems,
Rainwater is a valuable resource. We work to improve waterway health, provide opportunities to reuse rain water, and prevent flooding.
Unlike combined systems in Europe and other regions that can handle both wastewater and stormwater, a dedicated stormwater system system specifically channels rainwater away from the streets, rooftops, and over surfaces.
This approach helps prevent flooding, reduces warerlogging, and minimises the risk of damage to infrastructure and property, resulting in safe and functional urban environments.
In Western Australia, local authorities manage stormwater systems. However, because stormwater flows can cross local authority boundaries and require larger drainage systems, often a coordinated approach is needed.
This is especially important in cities like Perth, ensuring effective stormwater management to protect our infrastructure and the environment.
The role of Water Corporation
Water Corporation plays a major role in receiving stormwater discharge from drains managed by local authorities.
In urban environments, hard surfaces like rooftops, roads, and footpaths, prevent rain from soaking into the ground. This creates stormwater, which often flows from property drains to street gutters operated by local councils. Gutters may connect to large pipe networks. These form our Water Corporation managed drainage systems.
What makes up our drainage system?
Our drainage network services about 407,000 properties. It consists of:
- 75 urban catchments
- more than 2,500 kilometers of both underground and above-ground drains, including parts of the South West and Great Southern network
- 6 regional drainage networks
Key parts of our drainage system include:
- Open channels
- Underground drains (both gravity and pressure mains of various shapes and sizes)
- Drainage pump stations - there are 46 drainage pump stations across the state, all in the metro area, owned and maintained by the Water Corporation
- Compensating basins - there are 343 compensation basins, 340 in the metro region and 3 in the South West region
- Bridges/culverts - there are 314 road bridges and 505 occupational crossings
Together with the Department of Water and Environmental Regulation (DWER), we promote stormwater management systems that integrate with the urban landscape, enhance land use function, improve micro-climate and provide amenity. Our Assets for Liveability Program recognises the opportunities presented by our broader assets supporting liveability across the state.
Stormwater washes litter, sediment, grease, oil and metals from roads and properties and carries them into our waterways. This can impact the health of our rivers, waterways and beaches. We work with local councils and state government agencies to manage the stormwater system and improve waterways.
Drain safety
Water Corporation and local councils share responsibility for drains for most of the drainage network. We work with local councils to provide a drainage system that safely carries stormwater away from built-up areas.
During a storm event, drains can become dangerous because:
- Water can rise quickly and unexpectedly
- Flowing water is powerful and can knock people over, even when its shallow
- slow moving flows can quickly become raging torrents
- Drains may contain hidden dangers such as slopes or rocks which are hard to see when it rains
For your safety, it’s important to keep away from stormwater drains when it rains. There is the potential for flowing stormwater to knock pets and small children off their feet, and they can become caught in drains.
If a pet or child does become caught in a drain, it could cost them their life, or endanger others who rescue them. Conditions can become very hazardous without warning.
The drainage system is an essential part of living in an urban area, but when it rains drains can become dangerous – so please don’t let your children and pets play near them.
If you see something that is not right, call Water Corporation 24/7 faults & outages on 13 13 75.