Kwinana Water Hardness & Quality Report (2026)

Water Corporation supplies drinking water to Kwinana, a southern Perth industrial suburb in Western Australia, serving the City of Kwinana local government area. The supply is a blend of groundwater drawn from the Gnangara Mound and Jandakot aquifers with desalinated seawater from the Kwinana Desalination Plant. Treatment happens at Water Corporation facilities, including the Kwinana plant, where water is remineralised, fluoridated, and disinfected to meet the Australian Drinking Water Guidelines.

The water originates from superficial aquifers on the Swan Coastal Plain. The Gnangara Mound, a primary groundwater source in the north, is situated within limestone and aeolianite formations of the Pleistocene Tamala Limestone. As groundwater filters through these mineral-rich strata, it picks up dissolved calcium and magnesium carbonates, leading to a naturally hard water profile. Although the desalinated component is initially very soft, the remineralisation process and the significant contribution from the hard groundwater mean the overall supply remains hard.

This hard water can lead to substantial limescale buildup on appliances and plumbing fixtures. Items like kettles, water heaters, dishwashers, and showerheads are particularly susceptible, which can decrease their efficiency and shorten their lifespan. Homeowners experiencing white deposits or reduced water flow may benefit from regular descaling with vinegar, fitting scale filters to water inlets, or installing a water softener. While softening can be advantageous for homes with high water usage, it's advisable to monitor sodium levels. The water's pH is 7.64, turbidity is 0.3 NTU, and total dissolved solids are 576 mg/L, all within guideline limits.