Highett Water Hardness & Quality Report (2026)

South East Water Corporation supplies drinking water to Highett, a suburb in Melbourne's Bayside area, Victoria, Australia. The utility draws from a network of protected reservoirs in the Yarra catchment, including Silvan Reservoir near Mount Dandenong, Cardinia Reservoir southeast of Melbourne, and others like Thomson and Upper Yarra further afield. Water is treated at plants such as the Frankston Treatment Plant serving southeast zones, with distribution through extensive pipelines to over 1.6 million customers across Melbourne's southeast, including Highett within the City of Bayside. The system emphasises closed catchments to maintain pristine quality, with conventional treatment involving coagulation, flocculation, sedimentation, filtration, and chlorination.

The Yarra River watershed spans the forested highlands of Victoria's Central Ranges, with reservoirs capturing runoff from granitic batholiths and folded Paleozoic sediments. Lacking extensive carbonate aquifers or dolomite formations, the geology features quartzose sandstones, shales, and granodiorites from the Lachlan Fold Belt, contributing to very soft water with low mineral content. Peat bogs and humic soils in the catchments add slight organic acidity, further limiting hardness ions, while the absence of gypsum or limestone dissolution keeps the supply characteristically soft across metro zones.

Because the water is soft, Highett residents experience minimal limescale buildup in kettles, pipes, or washing machines, reducing maintenance needs compared to harder regions. Soap and detergents lather easily, potentially requiring less usage, though very soft water can sometimes corrode older galvanised pipes faster. No water softener is recommended; instead, focus on occasional descaling of high-use appliances like coffee machines and monitoring for any blue staining from copper leaching in acidic soft water. Boilers and heaters last longer without hard deposits. South East Water's 2021-22 report confirms compliance with Australian Drinking Water Guidelines, featuring neutral pH around 7.5-8.0 and low turbidity post-filtration. No notable lead or copper exceedances, with corrosion control via pH adjustment; PFAS levels are undetectable or well below health limits in protected catchments.