The published figures
These are Water Corporation 2024–25 figures for the Dwellingup supply zone, taken from the utility’s own annual reporting — not estimates, and not our measurements.
| Parameter | Dwellingup | What it means |
|---|---|---|
| Hardness (as CaCO3) | 29 mg/L | Soft — aesthetic parameter, no health limit |
| Total dissolved solids | 149 mg/L | Mineral content; drives taste, not safety |
| pH | 6.93 | ADWG range 6.5–8.5 |
| Sodium | 36 mg/L | Relevant on a sodium-restricted diet |
| Chloride | 70 mg/L | Contributes to salty taste at higher levels |
| Iron | 0.05 mg/L | Staining; ADWG aesthetic guideline 0.3 mg/L |
| Manganese | 0.004 mg/L | Staining; ADWG aesthetic guideline 0.1 mg/L |
| Fluoride | Added | Removed only by RO or distillation |
| Disinfectant | Chlorine | Standard carbon removes it easily |
That places Dwellingup as the 28th hardest of Perth’s 28 zones — that is, among the softest, against a network median of about 89 mg/L. Compared with the hardest zone in the network (Two Rocks / Yanchep at 228 mg/L), this water carries a fraction of the mineral load.
What the hardness figure means here
At 29 mg/L this is soft water — one of the softest supplies in the Perth network. Scale on kettles and heating elements should be minimal, soap and detergent go further, and there is essentially no case for a water softener or a scale conditioner here. If you have been quoted for scale treatment in Dwellingup, the data does not support it.
If you need that figure in another unit — grains per gallon for a US softener spec, or German degrees for a European appliance — our hardness converter handles it. 29 mg/L is about 1.7 gpg.
Where this zone’s water comes from
This zone is supplied from surface water — dams and catchments rather than bores. Rainfall collected in the hills has had little contact with mineral-bearing rock, which is why the surface-fed zones are the softest in the entire Perth network, and dramatically softer than the northern groundwater suburbs.
Total dissolved solids sit at 149 mg/L — low by Perth standards, reflecting the source. Water here tastes cleaner and less mineralised than in the groundwater-fed north of the city.
Perth is unusual among Australian capitals in how much its water varies by address — the network runs from 29 mg/L to 228 mg/L, soft to very hard within one city from one utility. A city-level average is close to meaningless here. See the full zone lookup for every locality.
On source descriptions: the supply mix above is our own characterisation of what typically feeds this zone, not a Water Corporation locality-to-plant mapping — the utility publishes water quality by locality but not a definitive source breakdown per zone. Perth’s Integrated Water Supply Scheme is integrated by design: streamflow, groundwater, desalinated seawater and groundwater replenishment are blended and redirected across 15 dams, six groundwater treatment plants and two desalination plants according to demand and season. Treat the source line as indicative of character rather than a fixed fact, and the measured figures in the table above as the authoritative part of this page.
Zones with similar water
If you are comparing suburbs — moving, or working out whether a neighbour’s filter advice applies to you — these are the Perth zones closest to Dwellingup on hardness:
| Supply zone | Hardness | Band | Source |
|---|---|---|---|
| North Dandalup / Peel region | 42 mg/L | Soft | Surface water |
| Pinjarra / Murray Bridge | 46 mg/L | Soft | Desalination + surface water blend |
| Tamworth Hill / Rockingham | 47 mg/L | Soft | Desalination dominant |
Two zones at similar hardness can still behave differently: groundwater zones carry more iron and manganese, while desalination-fed zones stay more consistent through the year.
What to actually filter for in Dwellingup
For chlorine taste: Perth is disinfected with free chlorine, not chloramine, which is the easy case. Any standard activated carbon filter — jug, benchtop or under-sink — handles it, and refrigerating water in an open jug lets chlorine dissipate on its own.
For scale: no meaningful case. At this hardness a softener or conditioner solves a problem you do not have. Treat any scale-treatment quote in this zone with scepticism.
For fluoride: Perth supply is fluoridated. Carbon does not remove fluoride — only reverse osmosis or distillation does.
Frequently asked questions
Is the water hard in Dwellingup?
Soft — 29 mg/L as CaCO3 on Water Corporation 2024–25 data, ranking 28th of Perth’s 28 supply zones.
Do I need a water softener in Dwellingup?
No. At this hardness there is no meaningful scale to treat, and a softener would solve a problem you do not have.
Does Dwellingup water contain fluoride?
Yes — Perth’s supply is fluoridated. Activated carbon does not remove fluoride; reverse osmosis or distillation is required.
Where does this data come from?
Water Corporation 2024–25 published drinking water quality reporting for this supply zone. We take no commissions and carry no paid placements — see who to trust for filter advice.