Ermington Water Hardness & Quality Report (2026)

Sydney Water Corporation supplies Ermington, New South Wales, as part of Greater Sydney's metropolitan area. The primary source is Warragamba Dam on the Warragamba River, supplemented by reservoirs including Prospect, Cordeaux, Woronora, and Tallowa Dam on the Shoalhaven River. Water is treated at major plants such as Prospect Water Filtration Plant, serving Ermington via the distribution network. The service covers the City of Parramatta local government area where Ermington is located, providing drinking water to over 5 million residents across Sydney's suburbs. The catchment spans the Greater Sydney region, primarily the Warragamba Dam catchment covering 21,000 square kilometres of bushland.

Key geological features include Triassic-age Hawkesbury Sandstone and associated shales, which dominate the watershed. Unlike limestone-dominated areas, this geology yields water with low dissolved mineral content, producing a characteristically soft supply. Seasonal rainfall and runoff through these formations maintain the naturally low mineral profile before treatment. The underlying formations are relatively low in calcium and magnesium-bearing minerals like limestone or dolomite, resulting in the naturally soft water character observed in the treated supply.

As soft water, Sydney's supply produces minimal limescale buildup, posing low risk to appliances like kettles, hot water systems, and washing machines. Soap lathers easily without excess detergent needed, and skin or hair dryness from minerals is not an issue. No softener is required or recommended; standard maintenance suffices. The soft nature enhances water efficiency in households without scaling concerns. Sydney Water maintains excellent compliance with Australian Drinking Water Guidelines.