Perth has hard water in some suburbs and soft water in others. Two Rocks in the far north averages 228 mg/L (as calcium carbonate). Mandurah in the south averages 50 mg/L. WaterScore calculated a city average of 96 mg/L from Water Corporation data.
So “does Perth have hard water?” has no single answer for the whole city. Your supply zone decides it.
This guide gives Perth water hardness by locality, from the Water Corporation 2024-25 report. It explains why the north is harder than the south. It also covers what those numbers mean for your skin, hair and fittings. For the national picture, see our guide to hard water in Australia.
Important: this article is general information about water quality. A shower filter is not a medical treatment for eczema or any skin condition. If you have a diagnosed skin condition, consult a dermatologist.
Does Perth have hard water?
Parts of Perth do. The north is the hard end. Two Rocks averages 228 mg/L and Yanchep averages 198 mg/L. Wanneroo averages 125 mg/L, and Mandurah in the south only 50 mg/L. So hardness in Perth depends on which supply zone feeds your street.
The spread is the real story here. One Perth household can live with scale on every tap. Another household, 60 km away, can go years without it. Both drink water from the same utility.
Water Corporation publishes a hardness figure for each supply locality every year. It reports a mean and a maximum for the reporting year. We use the 2024-25 tables below.
Perth water hardness by locality
Perth’s supply localities cover a wide hardness range, from 29 mg/L up to 228 mg/L. These figures come from Water Corporation’s 2024-25 Perth aesthetic tables, covering 1 July 2024 to 30 June 2025.
| Locality | Average (mg/L) | Maximum (mg/L) |
|---|---|---|
| Two Rocks | 228 | 240 |
| Yanchep | 198 | 210 |
| Neerabup | 190 | 200 |
| Wanneroo | 125 | 150 |
| Mundaring | 98 | 99 |
| Mandurah | 50 | 52 |
Two Rocks is the hardest locality in the table. It’s the only Perth-region entry with an average above 200 mg/L. Yanchep sits just under that mark. Neerabup is close behind at 190 mg/L. Wanneroo is well below, at 125 mg/L.
Mundaring, up in the hills, averages 98 mg/L. That’s middle of the pack, not soft. The softest supply in the region drops as low as 27 mg/L, at Dwellingup.
One warning about suburb lists you find online. Water Corporation reports by supply locality, not by suburb name. Joondalup, Clarkson and Butler aren’t listed localities in the 2024-25 tables. We give no hardness figure for them. If you see one quoted, ask which table it came from.
Why is water hard in Perth’s north?
Perth draws on four sources. Groundwater is 30-40% of scheme water. Desalinated seawater is another 30-40%. Dams and groundwater replenishment make up the balance. Groundwater from the northern aquifers moves through limestone for decades. It picks up calcium and magnesium, so the north reads harder.
The Gnangara groundwater system sits under Perth’s northern suburbs. Water Corporation calls it the largest groundwater source in WA. The utility puts Perth’s groundwater at around 40% of the Integrated Water Supply Scheme. It holds three aquifers: superficial, Leederville and Yarragadee.
Limestone is mostly calcium carbonate. Water sitting in it for years dissolves some of that rock. The longer the contact, the more mineral the water carries.
Desalinated seawater behaves differently. It comes out of the plant very low in hardness. Dam water from the hills is low too. So a locality’s reading depends on the blend it gets, and that blend changes through the year.
Be careful with the old claim that most of Perth’s water is groundwater. Water Corporation’s own source mix update from May 2024 puts groundwater at 30-40% and desalination at 30-40%. Neither one is the majority.
What counts as hard water in Australia?
The Australian Drinking Water Guidelines set four bands. Under 60 mg/L is soft, and can be corrosive. From 60 to 200 mg/L is good quality. From 200 to 500 mg/L brings increasing scaling. Over 500 mg/L means severe scaling. The 200 mg/L mark is an aesthetic guideline, not a health limit.
Run Perth through that scale and the picture gets clearer. Two Rocks is the only locality in the table past 200 mg/L. Yanchep, Wanneroo and Mundaring all sit inside the “good quality” band. Mandurah is soft.
The Australian Drinking Water Guidelines page is the source for those bands. Read it yourself before you trust any “very hard” label on a suburb page.
You’ll see other scales online with bands like “moderately hard” and “very hard”. Those come from a common industry scale, not from the ADWG. We don’t use them on this site. When we say a locality is hard or soft, we mean the ADWG bands above.
Nothing in that scale is about safety. Perth tap water is safe to drink at every one of these readings. Hardness is a comfort and a maintenance question.
What does hard water do in a Perth home?
Hard water reacts with soap. That reaction leaves a residue on skin, hair and glass. In harder northern localities you see it faster. Scale turns up on the showerhead, the kettle and the shower screen. Skin can feel dry and tight. Hair can feel rough and look dull.
Scale is the visible part. White crust builds up around tap outlets and on the face of the showerhead. In a Two Rocks or Yanchep home this shows within weeks. In Mandurah it takes far longer.
Skin is the part people notice second. Soap doesn’t rinse away cleanly in harder water. A thin film stays behind. If you want the detail on that, our guide, does hard water affect skin, covers it in full.
Hair picks up the same residue. It can feel heavy and rough after washing. Shampoo lathers poorly, so people use more of it and still feel unclean.
Moving into a northern suburb is often when this starts. Nothing changed in your routine. Only the water did.
How does Perth compare with other cities?
Perth has no single hardness figure to compare. Its northern localities read hard. Its southern ones read soft. Adelaide’s metro average sits close to Perth’s city average. Melbourne is soft almost everywhere. Sydney is softer again. So the supply zone matters more than the city name.
Adelaide runs on River Murray and reservoir water instead of aquifers. Its metro average is around 97 mg/L. That’s very close to Perth’s 96. See adelaide water hardness for the suburb detail and the SA Water lookup.
Melbourne is the other end. Most of its supply comes from protected mountain catchments, so the water picks up few minerals. Our Melbourne guide, is melbourne water hard or soft, settles that before you assume any Victorian suburb is hard.
Sydney sits lower still. Sydney Water puts greater Sydney near 57 mg/L, which is soft. That is about a quarter of the Two Rocks reading. Our Sydney guide covers sydney water hardness, sourced from the utility’s own figure.
So the honest summary is this. Perth’s north holds the hardest readings in the Water Corporation tables. Its city average of 96 mg/L still sits under Adelaide’s 97.
Shower filter for Perth water
You can’t change your suburb’s supply zone. You can change the water at the point it hits your body.
Our shower head filter fits between your shower arm and your showerhead. Ours uses PP cotton, stainless steel mesh, KDF-55, calcium sulfite, activated carbon and mineral and ceramic media. It reduces chlorine, heavy metals and sediment. It also reduces calcium and magnesium. It may help limit limescale on the showerhead and fittings.
It fits standard 1/2-inch shower arms. That covers wall-mounted, handheld, rain and combo showers. You need no tools. Thread tape and rubber rings come in the box.
Is it worth it in every Perth suburb? Honestly, no. In Mandurah at 50 mg/L, hardness isn’t your problem. Chlorine might still be. In Two Rocks, Yanchep or Wanneroo, the mineral load is the daily complaint. A filter works on the water you actually stand under.
A whole-house system treats every tap in the house. That’s a bigger job and a bigger spend. Your issue is how your skin and hair feel after a shower. Then the shower is the place to fix it.
Frequently asked questions
Is Perth water hard or soft?
Both, depending on your locality. Two Rocks averages 228 mg/L and Yanchep averages 198 mg/L, so the far north is hard. Wanneroo averages 125 mg/L and Mundaring averages 98 mg/L. Mandurah averages 50 mg/L, which the ADWG calls soft. WaterScore puts the city average at 96 mg/L.
Which Perth suburbs have the hardest water?
Two Rocks has the hardest water in Water Corporation’s 2024-25 Perth tables, averaging 228 mg/L. Yanchep follows at 198 mg/L. Neerabup averages 190 mg/L and Wanneroo 125 mg/L. All four sit in Perth’s north. Joondalup, Clarkson and Butler aren’t listed, so we give no figure for them.
Why is Perth water hard?
Groundwater is 30-40% of Perth’s scheme water. Much of it comes from the Gnangara system under the northern suburbs. That water moves through limestone for decades and dissolves calcium and magnesium. Desalinated seawater supplies another 30-40% and is much lower in hardness, so readings vary by supply zone.
Does Perth hard water affect skin and hair?
It can. Hard water reacts with soap and shampoo. The residue doesn’t rinse off cleanly, so skin can feel dry and tight after a shower. Hair can feel rough and look dull. People in the harder northern localities notice it most. It isn’t a medical condition.
Does a shower filter help with Perth hard water?
It can help. A multi-stage shower filter reduces chlorine, heavy metals and sediment. It also reduces calcium and magnesium in the water before it reaches you. It may help limit limescale on the showerhead. It won’t change the water at your other taps. Results differ from person to person.
What is the softest water in the Perth region?
Mandurah averages 50 mg/L. Several supply localities read lower still. Bold Park averages 49 mg/L, Tamworth Hill 47 and Pinjarra 46. Dwellingup is the softest in the 2024-25 tables. It averages 29 mg/L, with readings down to 27. Under 60 mg/L the ADWG calls water soft.
Your shower sits in one of Perth’s harder northern zones. Fitting a shower filter for hard water is the smallest change you can make. It reaches your skin and hair every day.
Last reviewed September 2026 by Lena Hartman
Disclaimer: this article is general information about water quality, not medical advice. A shower filter is not a medical treatment for eczema or any skin condition. If you have a diagnosed skin condition, consult a dermatologist.