Hillarys Water Hardness & Quality Report (2026)

Hillarys' drinking water is supplied by the Water Corporation via the Integrated Water Supply Scheme (IWSS), incorporating Gnangara Mound groundwater and Kwinana and Binningup Seawater Desalination Plant contributions for the City of Joondalup LGA outer northern Perth distribution in Western Australia. Water hardness in Hillarys is measured at 152 mg/L — classified as moderately hard — within the Australian Drinking Water Guidelines (ADWG) aesthetic guideline of 200 mg/L published by NHMRC. Hillarys — a coastal suburb in the outer northern Perth City of Joondalup LGA, internationally known for the Hillarys Boat Harbour and Sorrento Quay shopping, dining, and marina complex, the AQWA Aquarium of Western Australia, the Hillarys to Scarborough Coastal Path cycling and walking trail, and the popular Indian Ocean beachside coastal lifestyle — receives moderately hard supply from the outer northern Joondalup IWSS distribution consistent with the Gnangara Mound groundwater fraction.

Hillarys' moderately hard supply reflects a moderate Gnangara Mound groundwater fraction in the outer northern Joondalup IWSS distribution. The Gnangara Mound groundwater percolates through the Superficial Aquifer and Tamala Limestone — the porous Eocene carbonate formation of the Swan Coastal Plain — accumulating moderate dissolved calcium, magnesium, and sulphates. At 152 mg/L and TDS 377.3 mg/L, Hillarys sits in the moderately hard range of the Perth IWSS distribution, harder than inner Perth softer sub-zones but considerably softer than the very hard outer Perth sub-zones (Hamilton Hill 209 mg/L, Waikiki 234.5 mg/L), reflecting the moderate Gnangara Mound fraction at the Joondalup coastal distribution.

Hillarys residents can expect moderate limescale on taps and in kettles — descaling every four to six weeks is typical. Hot water systems benefit from regular inspection. Solar hot water systems in WA's climate benefit from periodic servicing. Under WA water restrictions, garden irrigation is limited. The low lead reading (0.002 mg/L) is excellent. The Water Corporation provides water quality information at watercorporation.com.au, with all ADWG health standards met. Hillarys' Boat Harbour marina community and the Joondalup coastal residential corridor benefit from supply meeting all ADWG standards.