Rowville Water Hardness & Quality Report (2026)

Rowville's drinking water is supplied by South East Water as water retailer, with bulk supply from Melbourne Water distributed through the south-eastern metropolitan network in Victoria. Water hardness in Rowville is measured at 99.5 mg/L — classified as slightly to moderately hard — within the Australian Drinking Water Guidelines (ADWG) aesthetic guideline of 200 mg/L published by NHMRC. Rowville, in the Knox LGA of Melbourne's outer south-east, receives supply from a distribution zone that incorporates a significant contribution from the Winneke Water Treatment Plant on the Yarra River at Yering Gorge, explaining the notably elevated hardness compared to the Melbourne CBD.

Rowville's elevated hardness reflects the Winneke Water Treatment Plant contribution to the south-eastern Knox distribution. The Winneke plant draws from the Yarra River at Yering Gorge, where the river traverses Devonian basalt flows and alluvial valley sediments of the Yarra Valley — calcium-richer geological terrain than the protected granite reservoir catchments that supply the softer inner Melbourne zones. This Yarra River-derived supply component is blended with the soft Thomson and Upper Yarra reservoir water in the south-eastern distribution network, producing the 99.5 mg/L hardness at the Rowville tap.

Rowville residents face moderate limescale accumulation on taps and in kettles — descaling every two to three months is typically needed. Hot water systems benefit from annual inspection to check for scale build-up. The elevated lead reading (0.004 mg/L) warrants briefly running the cold tap before use in older established homes. South East Water provides water quality information at southeastwater.com.au, with all ADWG health standards consistently met throughout the Knox supply zone.