Cairns Water Hardness & Quality Report (2026)
Water Hardness
Source
river
pH Level
7.2
neutral = 7.0
Lead
0.001 mg/L
✓ Below action level
TDS
95 mg/L
Est. Daily Cost
A$0.16
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 Cairns, your appliances are currently losing 7% efficiency due to mineral buildup.
| Appliance | In Cairns | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 7.9 yrs | 8.5 yrs | -7% |
| Washing Machine | 11.8 yrs | 12 yrs | -2% |
| Water Heater | 13.6 yrs | 15 yrs | -9% |
Regional Water Comparison
How Cairns compares to its nearest neighbours
| City | Hardness | Risk | Source |
|---|---|---|---|
| ▶ Cairns, Queensland | 50 mg/L | 🟢 Soft | river |
| Townsville, Queensland | 65 mg/L | 🟡 Moderately Hard | river |
| Mackay, Queensland | 67.5 mg/L | 🟡 Moderately Hard | mixed |
| Sunshine Coast, Queensland | 75 mg/L | 🟡 Moderately Hard | reservoir |
| Toowoomba, Queensland | 180 mg/L | 🔴 Very Hard | reservoir |
National Benchmark
How Cairns compares to the Australia average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Cairns | 50 mg/L | 🟢 None |
| Australia National Avg | 81 mg/L | 🟡 Low |
| Hobart Top Rated | 11 mg/L | 🟢 None |
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What Makes Cairns's Water Unique?
Local geology and source profile
Cairns' drinking water is supplied by Cairns Regional Council Water, sourced primarily from Lake Tinaroo (Tinaroo Dam) on the Atherton Tablelands in far North Queensland, supplemented by the Copperlode Falls Dam on the Barron River closer to the city. Water hardness in Cairns is measured at 50 mg/L — classified as soft — well within the Australian Drinking Water Guidelines (ADWG) aesthetic guideline of 200 mg/L published by NHMRC. The high-rainfall tropical catchments consistently deliver a fresh, low-mineral supply to the coastal city.
Cairns' soft supply reflects the volcanic and granitic geology of the Atherton Tablelands catchment. The Wet Tropics basalt and granite soils surrounding Lake Tinaroo are highly weathered due to the region's intense tropical rainfall, but the dominant mineralogy of these formations contributes only modest dissolved calcium and magnesium to catchment runoff. The exceptionally high annual rainfall of the Wet Tropics — often exceeding 1,500 mm on the Tablelands — further dilutes mineral loads in storage.
Cairns residents experience minimal limescale accumulation on taps, in kettles, and around shower fittings — descaling is an occasional rather than regular task at this hardness level. Hot water systems benefit from low scale build-up, sustaining heating efficiency with minimal maintenance. Under Queensland water restrictions, which can apply during the dry season between April and October, residents are encouraged to minimise outdoor watering. Cairns' tropical climate favours refrigerative air conditioning over evaporative systems, so mineral scale in cooling systems is less of a household concern than in drier regions of Australia.
Geology & Source: Supplied by Cairns Regional Council Water from Lake Tinaroo on the Atherton Tablelands — water draining through Wet Tropics basalt and granite soils of the tablelands dissolves modest minerals before flowing to the coastal city, producing soft supply at 50 mg/L.