Does Perth have hard water? The hardest and softest suburbs

Perth does not have one hardness figure. Official Water Corporation testing for 2024–25 found typical hardness readings from 29 mg/L in Dwellingup to 228 mg/L in Two Rocks, measured as calcium carbonate. Most of the 28 Perth supply localities sit in the Australian Drinking Water Guidelines band described as good quality for all domestic uses (60 to 200 mg/L). A smaller group is soft, under 60 mg/L. Only Two Rocks had a typical reading above the 200 mg/L aesthetic guideline.

Hardness is not a health limit in those guidelines. The water can still be safe to drink when it is hard. What changes is how it behaves at home: soap lather, spots on glass, and scale in kettles and hot water systems. Look up your suburb on the map or the Western Australia directory, then read the hardness scale if you want the mg/L bands in plain language.

As of 12 November 2026, WaterWatch suburb pages still display the 2023–24 report. This guide uses the newer 2024–25 official tables. Dwellingup was the softest Perth supply, and Two Rocks the hardest, in both years. An individual suburb's number can differ between the two reports.

How to read these figures

The numbers below are locality means from the Water Corporation Drinking Water Quality Annual Report for 1 July 2024 to 30 June 2025. A locality is a water quality zone, not always the same thing as a suburb. Many Perth suburbs are not sampled on their own. WaterWatch has a nearest-supply page for those places. It is a useful proxy, not a guarantee of the exact blend reaching one street. Much of Perth is fed by the blended Integrated Water Supply Scheme.

A typical reading is the mean of the year's samples. In Perth, hardness is often based on only two to five samples for the whole year. The peak is the highest sample. Yanchep is the clear example in 2024–25: the typical reading was 198 mg/L, which is just inside the good-quality band, but the peak was 210 mg/L. Water Corporation's published ticks usually follow the mean.

The softest and hardest Perth supplies, 2024–25

Softest typical readings, all under 60 mg/L:

1. Dwellingup, 29 mg/L
2. North Dandalup, 42 mg/L
3. Pinjarra, 46 mg/L
4. Tamworth Hill, 47 mg/L
5. Hills Direct, 48 mg/L
6. Bold Park, 49 mg/L
7. Mandurah, 50 mg/L
8. Melville, 54 mg/L
9. Hamilton Hill, 56 mg/L
10. Mount Eliza, 57 mg/L

Hardest typical readings:

1. Two Rocks, 228 mg/L. Above the 200 mg/L aesthetic guideline. Water Corporation notes that this higher hardness is characteristic of the source supplying the locality.
2. Yanchep, 198 mg/L, with a peak of 210 mg/L
3. Neerabup, 190 mg/L, with a peak of 200 mg/L
4. Wanneroo, 125 mg/L
5. Mirrabooka, 124 mg/L
6. West Yokine, 123 mg/L
7. Lexia, 118 mg/L
8. Whitfords, 113 mg/L
9. Mount Yokine, 108 mg/L
10. Mount Hawthorn, 106 mg/L

The unweighted mean of the 28 Perth locality means was 92 mg/L. That sits in the good-quality band. It is a poor description of any single suburb. Two Rocks is a standalone groundwater scheme, not part of the Integrated Water Supply Scheme, which helps explain why it sits apart from the rest of the metro ranking.

The far-northern supplies (Two Rocks, Yanchep and Neerabup) are the hardest group. The softest group is concentrated in the southern hills and Peel supplies, plus a few western and hills localities such as Bold Park and Hills Direct. Plenty of inner and middle suburbs sit between about 60 and 130 mg/L. "North is hard and south is soft" is too neat to be useful on its own. Check the locality, not the compass point.

Full Perth ranking, 2024–25 typical hardness

All figures are official means, in mg/L as calcium carbonate. The band uses the Australian Drinking Water Guidelines degrees of hardness. Names below are the WaterWatch page names. A few report names differ: Darlington is published as Greenmount/Darlington, and the Mount localities are published with the abbreviation "Mt."

1. Dwellingup 29, soft
2. North Dandalup 42, soft
3. Pinjarra 46, soft
4. Tamworth Hill 47, soft
5. Hills Direct 48, soft
6. Bold Park 49, soft
7. Mandurah 50, soft
8. Melville 54, soft
9. Hamilton Hill 56, soft
10. Mount Eliza 57, soft
11. Buckland Hill 63, good quality
12. Armadale & Kelmscott 75, good quality
13. Foothills 75, good quality
14. Darlington 77, good quality
15. Thomsons Lake 89, good quality
16. South Perth & Kewdale 94, good quality
17. Greenmount 95, good quality
18. Mundaring 98, good quality
19. Mount Hawthorn 106, good quality
20. Mount Yokine 108, good quality
21. Whitfords 113, good quality
22. Lexia 118, good quality
23. West Yokine 123, good quality
24. Mirrabooka 124, good quality
25. Wanneroo 125, good quality
26. Neerabup 190, good quality
27. Yanchep 198, good quality
28. Two Rocks 228, will increase scale formation

Some answers online apply a different chart and call readings above 180 mg/L "very hard". That is not the Australian guideline scale. On the Australian scale, "will increase scale formation" begins at 200 mg/L, and "high-level scaling" begins above 500 mg/L. No Perth locality mean reached 500 mg/L in 2024–25. Suburb pages on this site also show the household bands, so a place can be labelled very hard there and still sit inside the Australian good-quality band. The difference is explained in water hardness explained.

What hard or soft water means at home

The Water Corporation says hard water can leave spots on glasses and shower screens, and that more soap may be needed to get a lather. It can also matter when you buy a dishwasher. Scale can form in kettles and hot water systems. Soft water lathers easily. The guidelines also note that very soft water can be corrosive, depending on pH, alkalinity and dissolved oxygen. That is an aesthetic and plumbing issue, not a reason to treat the water as unsafe to drink.

If scale in a hot water system is your main concern, read the guide to hard water and your hot water system.

Find your suburb

Search any Perth suburb or WA town on WaterWatch, or open the map. If your suburb is not a sampled locality, the nearest-supply page shows the closest monitored points. For the method behind the typical reading and the regional rank, see About WaterWatch.