Stormwater Inflow Reduction Project

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Stormwater inflow reduction, keeping stormwater out of the sewer

Stormwater Inflow Reduction Project

The City of Coffs Harbour is working to reduce the amount of stormwater entering the sewer system across our Local Government Area.
Too much stormwater in the sewer network creates major issues for the environment, public health, and infrastructure.

What is stormwater inflow?

Stormwater inflow happens when rainwater enters the sewer system directly. This can occur through:

  • Illegal downpipe connections from homes or buildings
  • Low, damaged or blocked gully traps
  • Broken or uncovered manholes

Why is it a problem?

The sewer system is designed for wastewater, not stormwater. While a small amount of stormwater is unavoidable, too much can:

  • Overload pump stations and treatment plants
  • Cause environmental spills and public health risks
  • Increase operating costs and the need for costly upgrades (paid for by ratepayers)

Reducing stormwater inflow helps Council keep services affordable and reliable, while protecting the community and environment.

What is Council doing?

We are rolling out inspections and smoke and dye testing in residential, commercial, and industrial areas to find and fix stormwater inflow sources.

  • Smoke testing uses a non-toxic smoke (similar to theatre fog) pumped into sewer pipes. If smoke escapes from a roof gutter, it shows an illegal connection.
  • Dye testing uses a non-toxic dye added to water in gutters or drains. If it appears in the sewer, a stormwater connection has been confirmed.

This is a long-term project that will take several years to complete across all suburbs.

What does this mean for you?

If your property is connected to sewer, it will be inspected when testing comes to your area.

  • You’ll receive notice well in advance by letter, plus a reminder via letterbox the day before testing.
  • Updates will also be shared on Council’s social media, e-newsletters, and this webpage.
  • Inspectors only need to check external plumbing and drainage – they will not enter your home.
  • Police and Fire services are notified ahead of testing to prevent false alarms.

How you can help

Many property owners aren’t aware of illegal or faulty stormwater connections – often these were made by previous owners. You can help by:

  • Checking downpipes: Make sure they discharge to the ground or street, not the sewer.
  • Inspecting gully traps: Ensure rainwater can drain away freely. During heavy rain, check for water pooling around the gully and adjust landscaping or remove obstacles if needed.

By working together, we can reduce unnecessary costs, protect our waterways, and keep the sewer system working safely and efficiently.

For more details on testing, see the FAQs on this page.

Stormwater Inflow Reduction Project

The City of Coffs Harbour is working to reduce the amount of stormwater entering the sewer system across our Local Government Area.
Too much stormwater in the sewer network creates major issues for the environment, public health, and infrastructure.

What is stormwater inflow?

Stormwater inflow happens when rainwater enters the sewer system directly. This can occur through:

  • Illegal downpipe connections from homes or buildings
  • Low, damaged or blocked gully traps
  • Broken or uncovered manholes

Why is it a problem?

The sewer system is designed for wastewater, not stormwater. While a small amount of stormwater is unavoidable, too much can:

  • Overload pump stations and treatment plants
  • Cause environmental spills and public health risks
  • Increase operating costs and the need for costly upgrades (paid for by ratepayers)

Reducing stormwater inflow helps Council keep services affordable and reliable, while protecting the community and environment.

What is Council doing?

We are rolling out inspections and smoke and dye testing in residential, commercial, and industrial areas to find and fix stormwater inflow sources.

  • Smoke testing uses a non-toxic smoke (similar to theatre fog) pumped into sewer pipes. If smoke escapes from a roof gutter, it shows an illegal connection.
  • Dye testing uses a non-toxic dye added to water in gutters or drains. If it appears in the sewer, a stormwater connection has been confirmed.

This is a long-term project that will take several years to complete across all suburbs.

What does this mean for you?

If your property is connected to sewer, it will be inspected when testing comes to your area.

  • You’ll receive notice well in advance by letter, plus a reminder via letterbox the day before testing.
  • Updates will also be shared on Council’s social media, e-newsletters, and this webpage.
  • Inspectors only need to check external plumbing and drainage – they will not enter your home.
  • Police and Fire services are notified ahead of testing to prevent false alarms.

How you can help

Many property owners aren’t aware of illegal or faulty stormwater connections – often these were made by previous owners. You can help by:

  • Checking downpipes: Make sure they discharge to the ground or street, not the sewer.
  • Inspecting gully traps: Ensure rainwater can drain away freely. During heavy rain, check for water pooling around the gully and adjust landscaping or remove obstacles if needed.

By working together, we can reduce unnecessary costs, protect our waterways, and keep the sewer system working safely and efficiently.

For more details on testing, see the FAQs on this page.

Page last updated: 18 Sep 2025, 09:45 AM