Helping architects, designers, plumbers and home builders navigate onsite wastewater assessments, council approvals, and sustainable solutions across the South Coast, Southern Highlands, and Southern Tablelands.

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Introduction

Onsite wastewater management is often the last thing people think about when planning a build — but getting it wrong can stall approvals, blow out budgets and attract council penalties.

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This guide breaks down everything you need to know about wastewater assessments in Southern NSW: when you need one, what councils look for, how site conditions impact system design, and how to get your report approved the first time.

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1. When a Wastewater Assessment Is Required

You’ll need an onsite wastewater assessment any time wastewater load changes or the property isn’t connected to mains sewer. This includes:

• New builds on unsewered lots

• Granny flats or secondary dwellings

• Additions or alterations resulting in an additional wastewater load (addition of bedrooms)

• Subdivisions that create new lots

• Upgrades or replacements of old or non-compliant systems.

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💡 Pro Tip: Submit your wastewater report early — ideally during the design or DA stage — to keep your project moving.

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2. Greywater vs Blackwater

Understanding the difference helps you choose the right system:

Greywater

• Sources: Showers, baths, basins, washing machines

• Lower pathogen load; can be reused for sub-surface irrigation or toilet flushing

• Lower cost, easier maintenance

• Popular in towns like Berry, Milton, Moss Vale

Blackwater

• Sources: Toilets (and sometimes kitchens)

• Higher pathogen load; needs full treatment via septic, AWTS or advanced onsite system

• More expensive to install and maintain

• Standard for unsewered areas such as Nowra, Goulburn, Braidwood.

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👉 Best Practice: A combined greywater/blackwater system often ticks all the boxes for cost-effectiveness, sustainability, and council compliance.

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3. Council Requirements Across Southern NSW

Every council has slightly different rules for onsite wastewater management, shaped by local soils, rainfall, and environmental priorities:

• Shoalhaven City Council (South Coast): Focus on setbacks from waterways and flood-prone land; full wastewater assessments required.

• Wingecarribee Shire Council (Southern Highlands): Detailed WaterNSW catchment compliance

• Goulburn Mulwaree Council (Southern Tablelands): Requires wastewater management plans for secondary dwellings and system upgrades.

• Eurobodalla Shire Council (South Coast): Sustainability-driven; protecting coastal waterways is a priority.

• Yass Valley Council (Southern Tablelands): Requires percolation testing and in-depth site analysis.

• Queanbeyan-Palerang Regional Council: Strong focus on system sizing and compliance with NSW guidelines.

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💡 Expert Tip: A wastewater consultant can smooth the approval process and ensure your report meets the exact requirements of each council.

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4. Designing for Local Site Conditions

No two blocks are the same. Site conditions directly affect which wastewater system will work best:

• Soil type: Sandy soils allow flexible irrigation; clay-heavy soils require larger absorption areas.

• Rainfall: High-rainfall regions (Nowra, Kangaroo Valley) need careful drainage design; drier areas (Goulburn, Tarago) benefit from greywater reuse.

• Land slope: Steep sites may require pumped irrigation or engineered trenches.

💡 Pro Tip: Factor in soil tests, slope measurements, and rainfall data early. It’s far cheaper than redesigning later.

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5. Thinking sustainably  

Smart wastewater design not only keeps you compliant but also saves money and protects the environment:

• Reuse greywater for irrigation or toilet flushing

• Reduce mains demand with rainwater harvesting

• Design effluent disposal areas that protect waterways and soil health

• Consider composting toilets or integrated eco-systems for off-grid builds

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6. Checklist for Home Builders & Developers

Here’s how to streamline your project with a council-ready wastewater assessment from Southern Wastewater:

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Step 1: Provide Property Details

• Address, lot size, development details (new dwelling, additions, subdivision), and any site constraints

• Email to info@southernwastewater.com.au

• Full list of requirements at southernwastewater.com.au

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Step 2: Consultation & Quote

• We provide a quote and visit your property to assess soil and site conditions

• Preliminary disposal plan prepared for your review

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Step 3: Final Report & Council Submission

• After your endorsement, we deliver a final wastewater report (including soil results, maps and system diagrams) within 10–15 working days

• Ready for council submission, approval and build.

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7. Why Work with a Wastewater Consultant?

Partnering with a local consultant means:

• Accurate, compliant reports tailored to Shoalhaven, Wingecarribee, Goulburn, Eurobodalla, Yass Valley, Queanbeyan-Palerang and beyond

• Avoiding redesigns, approval delays and costly mistakes

• Systems that are right for your site’s soils, slope and rainfall

• Peace of mind that your council submission will get through first time.

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8. Our Simple Three-Step Process

We make onsite wastewater approvals easy:

1. Send Info: Email your property details to info@southernwastewater.com.au (full list on our website).

2. Site Visit & Quote: We assess soil and site conditions and prepare your preliminary plan.

3. Final Report: Within 10–15 working days you’ll have a complete, council-ready wastewater assessment.

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