Kellyville Water Hardness & Quality Report (2026)

Kellyville's drinking water is supplied by Sydney Water, treated at the Prospect Water Filtration Plant blending Warragamba Dam storage with Hawkesbury-Nepean river supply for the north-western Hills District in New South Wales. Water hardness in Kellyville is measured at 96 mg/L — classified as slightly to moderately hard — within the Australian Drinking Water Guidelines (ADWG) aesthetic guideline of 200 mg/L published by NHMRC. Kellyville, in The Hills Shire LGA of north-western Sydney's major residential growth corridor, receives a Prospect plant supply blend with a moderately elevated Hawkesbury-Nepean proportion, producing noticeably harder water than the standard inner Sydney supply (50 mg/L).

Kellyville's elevated hardness reflects the Hawkesbury-Nepean component in the north-western Hills District supply blend from the Prospect plant. The Hawkesbury-Nepean river system traverses Triassic alluvial plains and carbonate-cemented formations of the Cumberland Plain, dissolving substantial calcium bicarbonate before entering the treatment system. The Prospect plant's north-western Hills distribution corridor incorporates a proportionally greater Nepean-sourced component than the inner eastern zones, producing the 96 mg/L hardness intermediate between the very soft Warragamba supply (28 mg/L at Castle Hill) and the harder Baulkham Hills (160.5 mg/L) zones within the same Hills District LGA.

Kellyville residents will notice moderate limescale deposits on taps and in kettles — descaling every two to three months is typical. Hot water systems benefit from periodic inspection and element maintenance. The elevated lead reading (0.003 mg/L) warrants briefly running the cold tap before use in older homes in Kellyville's rapidly growing residential developments. Sydney Water provides water quality information at sydneywater.com.au, with all ADWG health standards met throughout the Hills north-west distribution network.