Reducing stormwater in our sewer system
The City of Coffs Harbour is running a long-term project to reduce the amount of storm water entering the sewer network.
When stormwater gets into the sewer it creates serious issues for the environment, public health, and infrastructure.
What is stormwater inflow?
Stormwater inflow occurs when rainwater enters the sewer system directly. This can be caused by:
- Illegal downpipe connections from homes or buildings
- Low, damaged, or blocked gully traps
- Broken or uncovered manholes
Why it matters
The sewer system is designed to carry wastewater, not rainwater. Too much stormwater can
- Overload pump stations and treatment plants
- Lead to environmental spills and public health risks
- Increase operating costs and require costly upgrades (funded by ratepayers)
By reducing stormwater in the sewer, we can keep services reliable and affordable while protecting our waterways.
What the City is doing?
The City is undertaking a long-term program of inspections and testing carrying out smoke and dye testing in residential, commercial, and industrial to find where stormwater is getting into the sewer and address stormwater inflow.
- Smoke testing: A non-toxic smoke (similar to theatre fog) is pumped into sewer pipes. If smoke escapes from roof gutters or other areas, it indicates an illegal connection.
- Dye testing: A non-toxic dye is introduced into gutters or drains. If the dye enters the sewer, a stormwater connection is confirmed.
This program will take several years to complete across all suburbs.
You’ll always be notified before testing takes place near your property. Inspectors will only need to look at outside drains and pipes, not inside your home.
What this means for residents
If your property is connected to sewer, it will be inspected when testing reaches your area.
- You will be notified in advance by letter, with a reminder delivered the day before testing.
- Updates will also be available through Council’s social media, e-newsletters, and this webpage.
- Inspectors will only check external plumbing and drainage; they will not enter your home.
- Police and Fire Services are advised ahead of testing to prevent false alarms.
How you can help
Sometimes stormwater gets into the sewer because of past building works or old connections that owners may not know about. You can help by:
- Checking that downpipes send rainwater to the ground or street, not into the sewer
- Making sure outside drains are clear and water can flow away easily
Together we can reduce unnecessary costs, protect the environment, and keep our sewer system working well.
For more details on testing methods and what to expect, see the FAQs.
What is the City doing?
The City of Coffs Harbour is running a long-term project to reduce the amount of stormwater entering the sewer system.
To do this, we are carrying out inspections and smoke and dye testing in residential, commercial, and industrial areas. These tests help identify where rainwater is entering the sewer network (for example, through broken pipes or illegal connections).
If a problem is found, the property owner will be notified and asked to arrange repairs. In many cases, fixing the issue is simple and inexpensive. If required, a licensed plumber can help.
During testing, City staff or contractors may need access to the outside of your property but will not enter your home. All workers will carry identification.
You may see white smoke coming from pipes or drains during testing. This smoke is non-toxic, not a fire, and is completely safe. Police and Fire Services are notified in advance to avoid false alarms.
What is stormwater inflow and infiltration?
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Stormwater inflow is when rainwater enters the sewer system directly. This can happen through:
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Illegal downpipe connections
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Damaged or low gully traps
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Broken or uncovered manholes
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Infiltration is when groundwater seeps into the sewer system through cracks, damaged pipes, or joints. This usually requires camera inspections to detect.
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Why is stormwater inflow a problem?
The sewer system is designed to carry wastewater, not rainwater. Too much stormwater can:
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Overload pumps and treatment plants
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Cause overflows and environmental pollution
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Create public health risks
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Lead to costly upgrades and higher rates
Reducing inflow helps the City keep services affordable, reliable, and environmentally safe.
Where does the excess stormwater come from?
Common sources include:
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Damaged or buried manholes
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Roofs, gardens, rainwater tanks, or driveways connected incorrectly to the sewer
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Broken or low gully traps
These connections are sometimes hidden underground, so property owners may not know they exist.
What does this mean for me?
You may not realise your property has an illegal connection. Some things to check include:
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Downpipes: If your roof gutters or rainwater tank overflow connect into a gully trap, this is likely an illegal connection.
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Gully traps: If a trap is damaged or at ground level, stormwater can flow into the sewer during rain.
If you’re unsure, a plumber can help check and fix connections.
What is an illegal connection?
Any plumbing that sends stormwater into the sewer is considered an illegal connection under NSW law.
Common examples are:
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Roof downpipes connected to the sewer
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Rainwater tank overflows plumbed into sewer drains
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Garden or driveway drains linked to the sewer system
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How do I know if my property is set up properly?
Look for downpipes, rainwater overflows, or drains leading into gully traps or sewer pipes. If you’re unsure, contact the City or a licensed plumber for advice.
How can I fix it?
Stormwater and sewer systems must be separate. Rainwater from roofs, tanks, and outdoor drains must be diverted to the street or onto your land, not into the sewer.
If you find a problem:
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Disconnect and redirect the stormwater
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Engage a licensed plumber if needed
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Contact the City for guidance if you’re unsure
What is smoke and dye testing?
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Smoke testing: A non-toxic smoke is pushed through sewer pipes. If smoke escapes from drains or gutters, it shows where stormwater is entering.
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Dye testing: A harmless dye is added to stormwater drains or gutters. If the dye appears in the sewer, it confirms a connection.
Both methods are safe, effective, and commonly used.
Will smoke enter my home?
No, smoke should not enter your home. If it does, this may indicate faulty internal plumbing that could also let sewer gases inside. If this happens, contact a licensed plumber immediately.
The smoke used is odourless, non-toxic, safe for people, pets, and plants, and will clear quickly with ventilation.
Do I need to do anything?
Yes, please:
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Watch for advance notices – you’ll receive letters and a reminder before testing in your area
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Make sure inspectors can safely access outdoor areas
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Secure pets (especially dogs) during testing
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Let us know if you have locked gates, alarms, or need special arrangements
You don’t need to be home during testing. Sewer services will not be interrupted and you can keep using your toilets, taps, and drains as normal.
Will fines be issued for illegal connections?
The City can issue fines under NSW law, but our priority is to work with residents to fix the problems.
We understand many issues were created by previous owners. In most cases, the City will contact property owners first to request that connections be corrected before considering enforcement.
Fixing these issues helps everyone by keeping costs down and protecting our waterways.