Killara Water Hardness & Quality Report (2026)

Sydney Water provides the drinking water for Killara, drawing from a network of reservoirs including Warragamba Dam, Prospect Reservoir, and Woronora Dam. These primary sources, along with others like Avon, Cordeaux, and Nepean Dams, collect water from the Greater Sydney catchment. This vast area, which includes parts of the Blue Mountains and Southern Highlands, drains into the Hawkesbury-Nepean River system. The raw water undergoes treatment at facilities such as the Prospect Water Filtration Plant and Woronora Water Filtration Plant before being distributed to over 5 million residents across Greater Sydney, including those in Killara, with no local groundwater supply.

The geology of the Greater Sydney catchment is dominated by Triassic-age formations, specifically the Hawkesbury Sandstone and the underlying Narrabeen Group shales and sandstones. This bedrock is largely composed of relatively inert sandstone, with very little limestone or dolomite present. Because carbonate rocks are the primary source of hardness minerals in water, their absence in this watershed means that very little calcium and magnesium leach into the surface water. This geological characteristic naturally produces a soft water supply that remains soft even after treatment.

Homeowners in Killara will find that the naturally soft water produces minimal limescale buildup in appliances like kettles and water heaters, which can extend their operational lifespan. You'll notice that soap lathers more easily, reducing the need for excess detergent. A water softener isn't necessary for this supply, helping to avoid potential issues like over-softening and corrosion. While the water quality is excellent, with low Total Dissolved Solids (TDS) of 137 mg/L and clear turbidity at 0.13 NTU, some samples have shown detectable E. coli, though Sydney Water employs multi-barrier treatments including filtration and disinfection to maintain safety.