Sewerage Pollution

Keeping stormwater out of the sewerage system

Sewage leaking and overflowing into local waterways can be a major pollution problem. Most urban waterways contain high levels of sewage contamination after rain. Our stormwater and sewerage systems are two separate underground pipe networks, but when stormwater gets into the sewerage system the extra water can impact on the ability of the sewerage system to cope with additional flows. When the pipes capacity is exceeded leaks and overflows of diluted raw sewage may occur. Overflows and leaking pipes are a serious source of pollution, a potential health risk and a nuisance to both the community and Council.

There are two ways for stormwater to get into the sewerage system:

  • Infiltration – usually caused by cracked or broken underground pipes which can be difficult to detect; and
  • Inflow – a direct flow of rainwater usually from an illegal roofing downpipe that has been directly connected to the sewerage system.

Property owners are responsible for maintaining the internal pipes on their property so that stormwater doesn’t leak into the sewerage system.

If you are unsure if stormwater is getting into your internal sewerage system there are a number of tests that can be conducted to find where potential issues may be including:

  • Camera investigation – a remote control CCTV camera can be inserted into the pipes to check what condition they are in; and/or
  • Smoke testing – which is non-toxic smoke directed into the sewer pipes and typically smoke will come out of any inappropriate connections or breaks to pipes.

Common ways stormwater can get into the sewerage system:

  • Cracks in sewerage pipes – usually caused by tree roots or movement in the ground.
  • Low-lying Gully – these are found just outside your house and generally have a loose-fitting grate that comes off easily in the instance of a sewer overflow. If the gully is low-lying in the ground, then it can let large amounts of stormwater into the sewerage system. A plumber can raise the gully or lower the ground around it.
  • Direct (illegal) connection – stormwater pipes are not allowed to be connected to the sewerage system. The effect of excess water in the sewerage system can cause overflows of raw diluted sewage further down the system.
  • Inspection Holes – poorly fitting, cracked, or broken inspection holes can let water into the system. If you notice any problems, contact Sydney Water directly.
  • Broken Pipes –Sydney Water is responsible for the wastewater network up to a property connection point. Property owners are responsible for the private wastewater pipes on their property up to and including that connection point, if you suspect any issues on your property, please contact a licensed plumber immediately.
  • Boundary Traps – are inspection points in the sewerage system and mark the place where your system joins the Sydney Water network. Damaged or cracked lids and/or concrete rims will allow unwanted stormwater water to enter the system. There will also be a problem if the vertical riser (the pipe under the boundary trap) is cracked.

Popping the pipe: how sewage gets out into the environment

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