Oatley Water Hardness & Quality Report (2026)

Oatley's drinking water is supplied by Sydney Water, treated at the Prospect Water Filtration Plant drawing predominantly from Warragamba Dam (Nepean River system) for the Georges River LGA inner southern Sydney distribution in New South Wales. Water hardness in Oatley is measured at 62.5 mg/L — classified as slightly hard — within the Australian Drinking Water Guidelines (ADWG) aesthetic guideline of 200 mg/L published by NHMRC. Oatley — a harbourside residential suburb in the Georges River LGA on the Como Creek inlet, known for the Oatley Park bushland on the Georges River National Park foreshore, the Oatley Bay foreshore and ferry wharf, the Oatley Hotel heritage pub, and the established inner southern Sydney residential community known for its leafy bushland setting — receives slightly elevated supply reflecting a minor elevation in the supply blend at the Oatley Georges River Prospect distribution sub-zone.

Oatley's slightly elevated hardness reflects a minor elevation in the Warragamba Dam supply blend, possibly with a minimal Hawkesbury-Nepean contribution at the Oatley Georges River Prospect distribution sub-zone. Warragamba Dam collects rainfall from the Blue Mountains sandstone plateau and Kanangra–Boyd granite uplands — chemically resistant terrain contributing negligible dissolved minerals. At 62.5 mg/L and TDS 111.8 mg/L, Oatley is slightly harder than the adjacent Mortdale (43.5 mg/L), Peakhurst (52.5 mg/L), and Sans Souci (52 mg/L) sub-zones, but dramatically softer than the very hard Carlton sub-zone (198 mg/L) in the same Georges River LGA — all confirming the supply distribution sub-zone variation across the southern Georges River Sydney Water network.

Oatley residents enjoy low limescale accumulation on taps and in kettles — descaling every two to three months is typically adequate. Hot water systems accumulate minimal scale. The very low lead reading (0.002 mg/L) is excellent. Sydney Water provides water quality information at sydneywater.com.au, with all ADWG health standards consistently met. Oatley's Georges River foreshore community benefits from this soft supply meeting all ADWG standards.