Australian Capital Territory Tap Water Quality

Water Sources

The Australian Capital Territory sources its drinking water from a system of four dams situated in protected catchments within and adjacent to the territory. The Cotter catchment, located in Namadgi National Park, includes Corin Dam, Bendora Dam, and the enlarged Cotter Dam. The Googong Dam, situated across the border in New South Wales, supplements the supply.

These catchments are predominantly closed to public access, set within national park and nature reserve land. This protection significantly reduces contamination risk and results in consistently high raw water quality.

Treatment Approach

Icon Water, the territory’s sole water utility, operates two main water treatment plants: Stromlo (the larger facility, treating water from the Cotter system) and Googong. Both use conventional treatment processes including coagulation, filtration, and disinfection with chlorine.

Because the protected catchments yield relatively clean source water, treatment requirements are less intensive than in jurisdictions that rely on open catchments or river systems. Fluoride is added to the ACT water supply in accordance with public health guidelines.

Key Challenges

Bushfire Risk

The ACT’s forested catchments are vulnerable to bushfire. The 2003 Canberra bushfires burned large areas of the Cotter catchment, degrading raw water quality for years afterward. Elevated turbidity, nutrients, and organic matter persisted in reservoir inflows, requiring operational adjustments at treatment plants. This event drove the decision to enlarge Cotter Dam, providing additional storage buffer.

Limited Source Diversity

With only four dams and no desalination or significant groundwater resources, the ACT has relatively limited supply diversity. The territory has invested in water efficiency programs and stormwater harvesting schemes to reduce per-capita demand.

Population Growth

Canberra is one of Australia’s fastest-growing cities. Ensuring water supply and infrastructure keep pace with development in new suburbs is a medium-term planning priority.

Regulatory Framework

ACT Health regulates drinking water quality under the Public Health Act 1997. Icon Water operates under a utility licence issued by the Independent Competition and Regulatory Commission (ICRC), which also sets pricing. Water quality monitoring results are publicly reported and benchmarked against the ADWG.

Infrastructure Highlights

The enlarged Cotter Dam, completed in 2013, increased the Cotter reservoir’s capacity from 4 gigalitres to 78 gigalitres. The Stromlo Water Treatment Plant was modernised following the 2003 bushfires to handle a wider range of raw water quality conditions.