If you’re researching on-site wastewater assessments in NSW, or you’re a homeowner, developer, planner or consultant working in the South Coast, Southern Highlands, or Southern Tablelands, you’ll quickly discover that many towns and villages in these regions do not have reticulated sewerage systems.

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This means property owners must rely on on-site sewage management systems (OSSM) such as septic tanks, AWTS, or treatment plants — and council approval is normally required.

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To save you in your planning, we've compiled a list of towns that are unsewered or partially unsewered across these regions. If you work in land development, plumbing, planning, wastewater design, environmental consulting or real estate, this guide will help you identify where on-site wastewater assessments are practically mandatory.

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South Coast NSW towns requiring On-Site Wastewater Systems

The NSW South Coast has a long list of smaller settlements that rely entirely on on-site systems due to the absence of town sewer. These towns commonly need OSSM approvals, land capability assessments, septic suitability reports, and designs for AWTS or septic systems:

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South Coast (Eurobodalla, Shoalhaven and Kiama Councils)

• South Durras

• Mystery Bay

• Congo

• Central Tilba

• Tilba Tilba

• Akolele

• Nelligen (upgrades are underway, as of early 2026)

• Kioloa

• Jamberoo 

• Rose Valley 

• Foxground

• Meroo Meadow

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Across the broader South Coast region, many rural residential and coastal pockets also remain unsewered, meaning on-site wastewater design is an ongoing requirement for new builds, alterations, dual occupancies and even some renovations.

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Southern Highlands NSW towns requiring On-Site Wastewater Systems

The Southern Highlands is known for its mix of heritage towns, rural villages and large semi-rural lots. While major centres like Bowral, Mittagong and Moss Vale have reliable sewer access, many small towns and outlying areas still depend on on-site sewage management systems.

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Southern Highlands Towns and Villages (Wingecarribee Council)

• Berrima

• Yerrinbool

• Glenquarry

• Bundanoon

• Exeter

• Kangaloon

• Penrose

• Fitzroy Falls 

• Robertson

• Sutton Forest

• Wingello

• Wildes Meadow

• Balmoral

• Hill Top

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Even towns that are partially sewered often have fringe or outer zones where properties must install their own wastewater treatment system. These areas usually require professional wastewater assessments to meet council guidelines, protect groundwater and ensure compliance.

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Southern Tablelands Towns requiring On-Site Wastewater Systems

The Southern Tablelands is one of NSW’s most decentralised regions, with many small villages lacking reticulated sewerage. Councils typically require detailed on-site wastewater reports, particularly on rural or environmentally sensitive land.

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Southern Tablelands (Hilltops & Goulburn-Mulwaree Councils)

• Bungonia

• Tarlo

• Frogmore

• Maimuru

• Milvale

• Monteagle

• Mount Collins

• Reids Flat

• Rugby

• Rye Park

• Thuddungra

• Wirrimah

• Parts of Wyangala

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These towns often sit on challenging terrain — from rocky soils to steep slopes — making professional wastewater design essential to ensure systems function effectively and meet NSW regulatory requirements.

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Why On-Site Wastewater Assessments matter in the regions

These communities require a professional report before approving development on unsewered land. These assessments typically include:

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• Soil testing and land capability analysis

• Effluent disposal design

• Hydraulic load calculations

• Environmental and buffer requirements

• Compliance with council OSSM strategies

• Mapping of site constraints (slopes, waterways, groundwater, vegetation)

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In summary

If you’re working in or near any of these towns in the South Coast, Southern Highlands, or Southern Tablelands, it is extremely likely that on-site wastewater assessments will be required.​ Knowing which areas are unsewered helps you:

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• Plan development more efficiently

• Meet council OSSM requirements

• Reduce delays in DA/CDC approvals

• Ensure environmental compliance

• Avoid costly redesigns or system failures. 

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Any questions? Don't hesitate to call us on 0435 575 403.