Water sources & supply systems

Water Whys

Customers often ask us why the taste of drinking water across our region varies so much.

The answer is simple - we manage a complex range and number of water sources from shallow bores and deep aquifers to pristine surface catchments and an award-winning roofwater harvesting system. They all have their own unique characteristics.

Surface water under is extracted under bulk water entitlement orders from the Gellibrand River (North and South) and Arkins Creek in the Otways, and from Victoria Range tributaries in the Grampians National Park. 

Water sourced from Konongwootong Reservoir, the Glenthompson Reservoir, the Dunkeld emergency storages and Rocklands Reservoir is also under bulk entitlement orders.

Additional surface water is collected in our reservoirs and via supply from Grampians Wimmera Mallee Water's Rocklands Reservoir and Willaura pipeline. 

The remainder of the water is supplied from groundwater bores, with 21 bores located throughout our 24,000-square-kilometre region.

We supply approximately 11,000 million litres of water to our customers every year. 

Water sources

Below is a summary of the water sources for localities serviced by Wannon Water.

Supply system  Water source  Locality 

Arkins Creek catchment, Gelibrand River catchment, groundwater flow - extracted from bores near Carlisle River.

Groundwater flow - extracted from bores at Albert Park, Warrnambool. 

Noorat/Glenormiston, Mortlake, Simpson, Cobden, Camperdown, Purnim, Terang, Warrnambool, Koroit, Allansford.

Warrnambool (Port Campbell Limestone Aquifer). 

Dilwyn Aquifer  Groundwater flow - numerous bores in localities serviced.  Portland
Port Fairy
Port Campbell, Peterborough, Timboon and Paaratte. 
Grampians  Victoria Ranges catchment (small streams and two bores) and Rocklands Reservoir. Hamilton, Tarrington, Cavendish, Dunkeld, Balmoral.

Bridgewater Formation

Groundwater flow - extracted at Tullich borefield. Casterton, Coleraine, Sandford, Merino, Henty.
Newer Volcanic Aquifer  Groundwater flow - extracted at bores in localities serviced Caramut, Penshurst, Mortlake
Glenthompson  Yuppeckiar Creek catchment and Willaura pipeline Glenthompson
Clifton Formation Groundwater flow - extracted from Macarthur bore  Macarthur 

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The Otway Supply System

Arkins catchment
This is a closed catchment composed of more than 750 hectares of native forest which forms part of the Great Otway National Park.

Gellibrand River north and south offtakes
The Gellibrand River catchment is composed of agricultural land, native forest and plantation forest along with numerous small urban developments. Water is extracted from two locations on the Gellibrand River. The North Otway system harvests water from the Gellibrand River near the Carlisle River township, and the South Otway system pumps water from the Gellibrand River at Chapple Vale. 

The Warrnambool Albert Park bores
The Albert Park bores are used to extract groundwater to supplement supply from surface water flows for Warrnambool, Koroit and Allansford, providing 10 per cent of their water requirements.

Carlisle borefield
Two bores situated near the Carlisle River township are used to supplement the supply from the Gellibrand River during times of low flow in the river.


There are several storages in the Otway system including Donald's Hill Reservoir south of Camperdown, Mount Ewen Reservoir east of Terang and the Warrnambool storage. The largest storage is Tank Hill Reservoir, north of Cudgee, which has a capacity of 750 million litres and provides a buffer, allowing us to meet demand in the peak summer period.

For more information on the Otway Supply System, visit our Information Sheets page.

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The Dilwyn Aquifer

The Dilwyn Aquifer is a large underground water source which stretches across much of South West Victoria and south-eastern South Australia. 

We extract water from the Dilwyn Aquifer at:

  • Portland
  • Port Fairy
  • Heywood
  • Dartmoor
  • Port Campbell

For more information on the Dilwyn Aquifer, please visit our Information Sheets page.

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Grampians Supply System

Water is harvested from various steams and groundwater bores located in the Grampians National Park.

The water is piped and stored in three major basins - Hayes Reservoir, Cruckoor Reservoir and Hartwichs Reservoir - located north of Hamilton.

The water is treated at the Hamilton Water Treatment Plant (WTP) to conform with the Australian Drinking Water Guidelines and is then supplied to Hamilton, and piped to Tarrington (nine kilometres) and Dunkeld (30 kilometres). Upstream of the Hamilton WTP, the water is diverted to the Cavendish system where it is disinfected prior to delivery to customers.

For more information on the Grampians Supply System, please visit our Information Sheets page.

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Balmoral Supply System

The Glenelg River catchment is comprised of national park, state parks, private agricultural land and feeds the Rocklands Reservoir. 

This reservoir is managed by Grampian Wimmera Mallee Water and has a 348,000-megalitre capacity.

Wannon Water pipes water from Rocklands Reservoir to the Balmoral Service Basin prior to treatment and distribution to the township of Balmoral.

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Newer Volcanic Aquifer

The Newer Volcanic Aquifer extends across the basalt plains of South West Victoria. We extract water from this aquifer at:

  • Penshurst
  • Caramut
  • Mortlake (to supplement the surface supply from Terang)

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Glenthompson Supply System

Water is harvested from two farmland catchment areas located to the south of Glenthompson and stored in the Glenthompson Reservoir. 

The water supply is supplemented through a pipeline from the township of Willaura which is supplied by Grampians Wimmera Mallee Water.

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Clifton Formation

The Clifton Formation forms a high yielding aquifer and occurs at economic depths of less than 200 metres.

The Macarthur bore intersects the confined Clifton Formation aquifer on the edge of town.

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