Stormwater and the Sewerage Network

How do I know the difference between sewer, sewage, sewerage and stormwater?

Sewage (or wastewater) is the used water that comes from your kitchen, bathrooms, laundry, sinks or other plumbing components in your home or business.

Sewer is the network of small and big pipes that carry wastewater. All sewers together form the sewerage.

Sewerage system refers to the infrastructure that collects, treats and disposes of the sewage from our homes and businesses via sewers.

Stormwater system is made up of gutters, downpipes, pits and drains that collect any water that runs off a site due to rainfall. These pipes and drains connect to your roof, driveway, garden, paths and roads.

These two systems are supposed to be separate and when stormwater gets into the sewerage system it can overload it leading to an overflow of diluted raw sewage. Overflows are a serious source of pollution, a potential health risk and a nuisance to the environment, community and Council.

For the majority of Hornsby Shire residents, wastewater services are provided by Sydney Water who operate externally to Council under an operating license to maintain services to all customers. There are, however, some rural properties and remote riverside settlements in Hornsby Shire that are not connected to the Sydney Water wastewater network. Instead, these properties rely on septic tanks and On-site Sewage Management systems (OSSMs).

Council has prepared a number of factsheets and manuals to help property owner guide OSSM maintenance efforts.

While Sydney Water manage the sewerage system, stormwater is largely managed by Hornsby Shire Council and very much influenced by the actions of our community. Stormwater is rainwater plus anything the rain carries along with it. As rainwater runs across different surfaces, it can pick up various types of pollutants including:

  • sediment from exposed soil
  • oil and grease from driveways and roads
  • leaves and animal droppings that collect in gutters
  • chemicals from lawns and gardens.

Stormwater is water from rain that does not soak into the ground. In urban areas, rain that falls on house roofs, paved areas like driveways, roads and footpaths, or flows from saturated gardens and grass fields, is carried away through stormwater pipes and canals to the ocean, via creeks and rivers. As it flows, this runoff collects and transports soil, pet manure, salt, pesticides, fertiliser, oil and grease, leaves, litter and other potential pollutants.

You don't need a heavy rainstorm to send pollutants rushing toward streams, wetlands, lakes and oceans. A running garden hose can supply enough water to wash pollutants down the drain. Even if your house is not on a waterfront, storm drains, and sewers efficiently convey runoff from your neighbourhood to the nearest body of water. Contrary to popular belief, the stormwater system does not carry storm water to wastewater treatment plants.

Thankfully, Council has a dedicated program to reducing the impact of stormwater on our waterways with an officer that routinely inspects elements of the Shire’s stormwater network to ensure the system operates as designed. Since 1997, Council also has installed over 400 stormwater quality improvement devices to trap pollutants as part of the Catchments Remediation Rate program.

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