Mosman Water Hardness & Quality Report (2026)
Water Hardness
Source
reservoir
pH Level
7.2
neutral = 7.0
Lead
0.001 mg/L
✓ Below action level
TDS
68.5 mg/L
Est. Daily Cost
A$0.13
energy & soap waste
Source: BOM National Performance Report & ADWG · Updated 2026
0–60
mg/L
Soft
61–120
mg/L
Moderately Hard
121–180
mg/L
Hard
180+
mg/L
Very Hard
Appliance Damage Report
In Mosman, your appliances are currently losing 5% efficiency due to mineral buildup.
| Appliance | In Mosman | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 8.3 yrs | 8.5 yrs | -2% |
| Washing Machine | 12.1 yrs | 12 yrs | — |
| Water Heater | 14 yrs | 15 yrs | -7% |
Regional Water Comparison
How Mosman compares to its nearest neighbours
| City | Hardness | Risk | Source |
|---|---|---|---|
| ▶ Mosman, New South Wales | 40.5 mg/L | 🟢 Soft | reservoir |
| Cremorne, New South Wales | 183 mg/L | 🔴 Very Hard | reservoir |
| Neutral Bay, New South Wales | 183 mg/L | 🔴 Very Hard | reservoir |
| Potts Point, New South Wales | 108.5 mg/L | 🟡 Moderately Hard | reservoir |
| Sydney Central Business District, New South Wales | 120 mg/L | 🟠 Hard | reservoir |
National Benchmark
How Mosman compares to the Australia average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Mosman | 40.5 mg/L | 🟢 None |
| Australia National Avg | 125 mg/L | 🟠 Moderate |
| Boronia Top Rated | 5 mg/L | 🟢 None |
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What Makes Mosman's Water Unique?
Local geology and source profile
Mosman's drinking water is supplied by Sydney Water, drawn from Warragamba Dam and the integrated Hawkesbury-Nepean reservoir system serving the Lower North Shore distribution network in New South Wales. Water hardness in Mosman is measured at 40.5 mg/L — classified as soft — well within the Australian Drinking Water Guidelines (ADWG) aesthetic guideline of 200 mg/L published by NHMRC. Mosman, the prestigious harbourside suburb on Sydney's Lower North Shore overlooking Middle Harbour and the Taronga Zoo foreshore, receives Sydney Water supply from the Warragamba-dominant distribution blend, with softness representative of the standard Sydney supply character.
Mosman's soft supply traces to the Warragamba Dam catchment geology in the Blue Mountains. The catchment drains through Triassic Hawkesbury Sandstone and Narrabeen Group shale — silica-rich, calcium-poor formations that resist chemical weathering and contribute negligible dissolved minerals to passing water. The northern harbour shore distribution zone, receiving a predominantly Warragamba-dominant supply, consistently delivers soft water to Mosman and the other Lower North Shore LGA suburbs, with hardness near the Sydney average of 50 mg/L.
Mosman residents enjoy minimal limescale accumulation on tap fittings, in kettles, and around shower fittings — descaling is an occasional rather than routine task. Hot water systems accumulate very little scale throughout their service life. Sydney Water provides water quality information at sydneywater.com.au, with all ADWG health standards consistently met. A benchtop carbon filter is popular in Mosman households for improved taste from the already soft supply, and the soft water is an everyday benefit for the many heritage homes with older plumbing infrastructure throughout the established Mosman residential streets.
Geology & Source: Supplied by Sydney Water from the Warragamba Dam and Nepean reservoir system serving the Lower North Shore Sydney distribution zone — the Mosman supply carries soft water at 40.5 mg/L, consistent with Sydney Water's characteristic Triassic Hawkesbury Sandstone catchment geology and the standard Warragamba-dominant Prospect plant supply blend for the northern harbour suburbs.