Blue Mountains Water Hardness & Quality Report (2026)

WaterNSW provides the Blue Mountains area with water as part of the wider Greater Sydney water network. The supply originates from the Nepean River system and its associated storage facilities, such as Medlow Dam and Greaves Creek Dam. These sources channel into the regional filtration and treatment plants that serve the local population. The Blue Mountains are situated within the Nepean River watershed, which is itself part of the larger Hawkesbury-Nepean system.

The region's geology is characterized by Triassic-age sandstones and shales belonging to the Sydney Basin. These rock types are rich in silica and contain very few soluble carbonate minerals. Consequently, the water drawn from these formations is soft, aligning with the general water quality found throughout Greater Sydney.

Because the water is soft, homeowners in the Blue Mountains will notice less scale buildup in everyday items like kettles, pipes, and appliances. You'll also find that soaps and detergents lather up easily. Appliances such as water heaters and dishwashers will require very little descaling. Installing a water softener isn't necessary and would likely be an unnecessary expense for residents. Separately, NSW Health and Sydney Water have confirmed that the tap water meets Australian Drinking Water Guidelines and is safe to consume. However, as a precaution, Medlow Dam and Greaves Creek Dam were temporarily taken offline in August 2025 due to slightly elevated levels of PFAS found in Medlow Dam, pending further investigation.