Canberra Water Hardness & Quality Report (2026)

Canberra's drinking water is supplied by Icon Water, drawn from the Cotter Dam and Corin Dam on the Cotter River, and the Googong Reservoir on the Queanbeyan River in the Australian Capital Territory. Water hardness in Canberra is measured at 25 mg/L — classified as very soft — significantly below the Australian Drinking Water Guidelines (ADWG) aesthetic guideline of 200 mg/L published by NHMRC. The combined system capacity of over 430 gigalitres supports the ACT's growing population.

Canberra's very soft water stems from the geology of the Brindabella Ranges and surrounding highlands. Catchment water filters through Ordovician granodiorite and rhyodacite tuff — igneous and metamorphic rocks that resist chemical weathering and contribute negligible calcium, magnesium, or bicarbonate to the supply. The high elevation, undisturbed bushland catchments, and relatively low evaporation rates at this altitude combine to preserve consistently low mineral loading year-round.

Canberra households see very little limescale on tap fittings or in kettles — descaling is rarely needed more than once or twice a year. Hot water systems experience minimal scale accumulation throughout their service life, substantially reducing maintenance costs. Some residents choose to install a whole-house carbon filter to address occasional taste variation after bushfire-affected summers that can impart smoky notes to the catchment. Under ACT water restrictions, staged outdoor watering rules apply during dry periods, making indoor appliance care and efficient hot-water management an everyday consideration for Canberra households.