Rockingham Water Hardness & Quality Report (2026)
Water Hardness
Source
mixed
pH Level
7.9
neutral = 7.0
Lead
0.003 mg/L
✓ Below action level
TDS
447.4 mg/L
Est. Daily Cost
A$0.54
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 Rockingham, your appliances are currently losing 23% efficiency due to mineral buildup.
| Appliance | In Rockingham | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 3.9 yrs | 8.5 yrs | -54% |
| Washing Machine | 7.2 yrs | 12 yrs | -40% |
| Water Heater | 8.7 yrs | 15 yrs | -42% |
Regional Water Comparison
How Rockingham compares to its nearest neighbours
| City | Hardness | Risk | Source |
|---|---|---|---|
| ▶ Rockingham, Western Australia | 172 mg/L | 🟠 Hard | mixed |
| Rockingham city centre, Western Australia | 149.5 mg/L | 🟠 Hard | mixed |
| Waikiki, Western Australia | 234.5 mg/L | 🔴 Very Hard | mixed |
| Warnbro, Western Australia | 108.5 mg/L | 🟡 Moderately Hard | mixed |
| Kwinana, Western Australia | 204 mg/L | 🔴 Very Hard | mixed |
National Benchmark
How Rockingham compares to the Australia average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Rockingham | 172 mg/L | 🟠 Moderate |
| Australia National Avg | 125 mg/L | 🟠 Moderate |
| Boronia Top Rated | 5 mg/L | 🟢 None |
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What Makes Rockingham's Water Unique?
Local geology and source profile
Rockingham's drinking water is supplied by the Water Corporation via the Integrated Water Supply Scheme (IWSS), blending Gnangara Mound limestone groundwater with desalinated supply from the Perth Seawater Desalination Plant at Kwinana for the City of Rockingham LGA outer southern Perth distribution in Western Australia. Water hardness in Rockingham is measured at 172 mg/L — classified as moderately hard — within the Australian Drinking Water Guidelines (ADWG) aesthetic guideline of 200 mg/L published by NHMRC. Rockingham — a popular outer southern Perth coastal community of beaches, the Rockingham foreshore, Safety Bay marine park, and the Kwinana industrial corridor, known as the gateway to Penguin Island — receives a moderately hard IWSS supply, softer than the harder inner Perth zones (Morley 237 mg/L, Duncraig 232 mg/L) due to proximity to the Kwinana desalination plant supply.
Rockingham's moderately hard supply reflects the IWSS blend of Tamala Limestone groundwater with a proportionally elevated desalinated supply component near the Kwinana desalination plant. The Gnangara Mound groundwater percolates through the Tamala Limestone — porous Eocene carbonate of the Swan Coastal Plain — where calcium carbonate readily dissolves. However, Rockingham's proximity to the Perth Seawater Desalination Plant at Kwinana means the local distribution receives a proportionally higher low-mineral desalinated supply fraction, moderating hardness below the harder inner Perth zones at 172 mg/L and TDS 447.4 mg/L.
Rockingham residents face moderate limescale build-up on taps and in kettles — descaling every three to four weeks is typical. Solar hot water systems popular in WA's climate accumulate scale; annual servicing is recommended. Under WA water restrictions, garden irrigation is limited to two days per week. The elevated lead reading (0.003 mg/L) warrants briefly running the cold tap before use. The Water Corporation provides water quality information at watercorporation.com.au, with all ADWG health standards consistently met throughout the Rockingham outer southern Perth supply zone.
Geology & Source: Supplied by the Water Corporation via the Integrated Water Supply Scheme blending Gnangara Mound groundwater with desalinated supply from the Perth Seawater Desalination Plant at Kwinana — the Rockingham City outer southern Perth supply carries moderately hard water at 172 mg/L with TDS of 447.4 mg/L, reflecting the IWSS blend at the outer southern Perth Rockingham distribution zone.