Colac Water Hardness & Quality Report (2026)

Colac's drinking water is supplied by Barwon Water (the regional urban water authority for south-western Victoria), drawing from the Barongarook Creek system and Otway Ranges catchment reservoirs via the Colac Water Supply Scheme for the Colac Otway Shire Council LGA regional distribution in Victoria. Water hardness in Colac is measured at 78.5 mg/L — classified as slightly hard — within the Australian Drinking Water Guidelines (ADWG) aesthetic guideline of 200 mg/L published by NHMRC. Colac — the regional service centre for south-western Victoria's Colac Otway Shire, situated on the shores of Lake Colac on the volcanic Corangamite Plains, known as the gateway to the Great Otway National Park and Otway Ranges, the Colac Otway agricultural and beef and dairy community, the Colac & District Historical Society Museum, and the key regional service hub for the south-western Victoria region between Geelong and Warrnambool — receives slightly elevated supply from the Barwon Water Colac regional distribution.

Colac's slightly elevated hardness reflects the moderate mineralisation character of the Barongarook Creek and Otway Ranges catchment geology in the south-western Victorian Barwon Water supply scheme. The Otway Ranges include Cretaceous and Tertiary sedimentary sequences, basalt from the Newer Volcanics geological province of the volcanic Corangamite Plains, and Eocene–Oligocene limestone formations — contributing moderate dissolved calcium and minerals compared to the very soft Yarra Ranges granite/dolerite catchments. At 78.5 mg/L and TDS 165.8 mg/L, Colac's supply is slightly elevated for a regional Victorian water supply, reflecting the moderate geological mineralisation of the Otway Ranges and Corangamite Plains source catchment.

Colac residents can expect occasional light limescale on taps and in kettles — descaling every two to three months is typically adequate. Hot water systems benefit from periodic inspection. The elevated lead reading (0.004 mg/L) warrants briefly running the cold tap before use. Barwon Water provides water quality information at barwonwater.com.au, with all ADWG health standards consistently met. Colac's Lake Colac community and the Otway Ranges regional hub benefit from a safe supply meeting all ADWG standards.