Water hardness in Mount Isa
75 mg/L moderately hard
Tap water in Mount Isa is moderately hard: 75 mg/L (4.4 gpg · 4.2 °dH · 7.5 °fH).
Source: Mount Isa Water Board, Drinking Water Service Annual Report 2024-2025 (2025-12) · data checked 2026-11-05
Range across supply zones: 70–78 mg/L.
Mount Isa Water Board's 2024-25 annual report gives 75.0 mg/L CaCO₃, with results from 70.0 to 78.0 mg/L, a narrow range. The supply is run by the water board rather than the council. Expect light to moderate scale on kettles and hot water fittings; descaling is usually enough.
Australian Drinking Water Guidelines: aesthetic target ≤ 200 mg/L CaCO₃.
Water data
| Total hardness | 75 mg/L |
|---|---|
| Utility | Mount Isa Water Board (MIWB) |
How Mount Isa compares
- Tap water in Mount Isa is 12 % softer than the median of the 307 cities we track in Australia (85 mg/L).
- By hardness it ranks 164 of 307 in Australia (1 = hardest); 47 % of these cities have softer water.
- In Queensland it is number 10 of 29 cities; the regional median is 68 mg/L.
Ranking of the hardest and softest water in Australia →
What it means at home
- Visible kettle scale every few weeks; vinegar or citric acid is enough.
- Water heater and washing machine: some long-term scale; a scale inhibitor slows it.
- Dishwasher: medium salt setting.
- Softener optional; pays off mainly with a gas boiler or tankless heater.
How much salt will you use for softening?
Optional. A scale inhibitor or a small softener protects the heater; soap savings are modest.
Descale a coffee machine or kettle about every 3 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Mount Isa
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 4 °dH |
| AEG / Electrolux | 2 |
| Beko | 1st |
| Hoover | S1 |
| LG | H1 |
From each brand's manual for the model family named in the source; your model may differ, so check its manual. All brands and how to change the setting →
FAQ
Is Mount Isa water hard or soft?
It is moderately hard: 75 mg/L as CaCO₃ (4.4 gpg, 4.2 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Mount Isa safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. Australian Drinking Water Guidelines: aesthetic target ≤ 200 mg/L CaCO₃.
How many grains per gallon is Mount Isa water?
4.4 gpg, equal to 4.2 °dH, 7.5 °fH or 75 mg/L calcium carbonate.
What dishwasher salt setting should I use in Mount Isa?
For 75 mg/L (4.2 °dH) check your manufacturer's table: level 2–3.
Do I need a water softener in Mount Isa?
Not essential; a scale inhibitor protects the heater cheaply.
Source
Source: Mount Isa Water Board, Drinking Water Service Annual Report 2024-2025 (2025-12). Method: figure published by the water supplier. Mount Isa Water Board, Drinking Water Service Annual Report 2024-2025 · Outdated figure? Tell us