- ✓All mains water in WA's South West is safe to drink and meets Australian Drinking Water Guidelines — whether supplied by Water Corporation, Aqwest (Bunbury) or Busselton Water.
- →Bunbury (Aqwest) draws from the Yarragadee Aquifer — moderately soft water at around 100 mg/L hardness. Chlorine-disinfected. Fluoride added by Ministerial directive from June 2024.
- →Margaret River, Dunsborough, and Augusta are supplied by Water Corporation from surface water (Willowdale Dam and local sources) — generally softer than Bunbury, often below 80 mg/L.
- →Manjimup and Pemberton receive surface water from local dams — among the softest water in regional WA. Hardness often below 60 mg/L.
- !South West water is generally much softer than Perth. Whole-home TAC or softening systems that make sense in Perth's hardest suburbs are often unnecessary in most South West towns.
Who supplies water in the South West
Unlike Perth where a single provider (Water Corporation) covers the metro area, the South West has a more complex picture with multiple suppliers serving different towns:
- Aqwest (Bunbury Water Corporation): Serves Bunbury and most of the Greater Bunbury area, operating as an independent government trading enterprise. Draws primarily from the Yarragadee Aquifer.
- Busselton Water: Serves Busselton and surrounding areas, also an independent provider drawing from coastal plain groundwater (Yarragadee and Leederville aquifers).
- Water Corporation: Supplies most other South West towns including Margaret River, Dunsborough, Augusta, Manjimup, Pemberton, Bridgetown, Boyup Brook, Harvey, Collie and many smaller communities. Sources vary by town — surface water from local dams in forested areas, groundwater on the coastal plain.
Bunbury — Aqwest supply
Bunbury is served by Aqwest, which draws primarily from the Yarragadee Aquifer — a deep, ancient groundwater system that underlies much of the southwest coastal plain. Aqwest publishes its own annual water quality report separately from Water Corporation.
Key characteristics of Bunbury's water:
- Hardness: ~100 mg/L — Aqwest describes this as "moderately soft to slightly hard." Noticeable but not at Perth levels. Some scale formation on kettles and appliances over time.
- Disinfection: Chlorine — Aqwest uses chlorine (not chloramine) as its disinfectant. Standard carbon block filters are effective.
- Fluoride: Added from June 2024 following a 2020 Ministerial directive. Previously unfluoridated — residents who preferred fluoride-free water should note this change.
- Naegleria fowleri risk: Because Bunbury water exceeds 24°C in summer, Aqwest maintains strict chlorine monitoring for Naegleria fowleri — a rare amoeba that can cause a fatal brain infection if water enters the nose. The risk is from activities like diving into water, not from drinking. Aqwest's testing programme manages this effectively.
| Town / Area | Provider | Source | Hardness (approx.) | Disinfection |
|---|---|---|---|---|
| Bunbury | Aqwest | Yarragadee Aquifer | ~100 mg/L | Chlorine |
| Busselton / Dunsborough | Busselton Water | Yarragadee / Leederville | ~80–120 mg/L | Chlorine |
| Margaret River / Augusta | Water Corporation | Willowdale Dam (surface) | ~60–80 mg/L | Chlorine |
| Manjimup / Pemberton | Water Corporation | Local dams (surface) | ~40–70 mg/L | Chlorine |
| Bridgetown / Boyup Brook | Water Corporation | Local dams + groundwater | ~70–100 mg/L | Chlorine |
| Harvey / Australind | Water Corporation | Coastal groundwater | ~90–120 mg/L | Chlorine |
| Collie | Water Corporation | Harris Dam | ~60–80 mg/L | Chlorine |
Margaret River, Dunsborough and Augusta
These towns are supplied by Water Corporation from surface water sources — primarily Willowdale Dam and associated catchments near Margaret River, supplemented by local groundwater for some areas. Surface water from forested catchments in the South West tends to be softer and lower in minerals than groundwater from the coastal plain aquifers.
Water hardness in this area is typically in the range of 60–80 mg/L — softer than Bunbury and significantly softer than Perth. Some scale formation on appliances occurs but is modest. The primary taste concern is chlorine rather than hardness or mineral content.
Residents who have moved from Perth often notice that South West water feels different — softer, with less mineral character. This is consistent with the data: the forested catchment sources of the South West produce fundamentally different water to Perth's groundwater and desalination blend.
Manjimup, Pemberton and the forested south
Towns further south — Manjimup, Pemberton, Nannup — receive water from local dams in heavily forested areas. This is among the softest mains water in regional WA, often with hardness below 60 mg/L. The water profile is more similar to Melbourne's mountain catchment supply than to Perth's groundwater-heavy network.
The primary consideration for residents here is actually colour and tannin content — after heavy rain, water from forested catchments can have an earthy tint from natural organic matter. This is aesthetic, not a health risk, and typically resolves within days. A carbon block filter addresses both tannin taste and chlorine effectively.
Bore water in the South West
Many South West properties — particularly rural lifestyle blocks and farms — access bore water rather than or in addition to scheme water. Bore water quality in the South West varies significantly by depth and location:
- Shallow bores on the coastal plain (particularly near wetlands or low-lying areas) can have elevated iron, manganese, and iron bacteria — the same issues affecting Perth bore water users.
- Yarragadee aquifer bores (deeper, used by Aqwest for Bunbury's scheme supply) are generally of better quality but can still have elevated hardness and iron in some areas.
- Surface-accessed bores or shallow fractured rock bores near agricultural areas can have nitrate, coliform bacteria, or pesticide issues depending on land use history.
Bore water in the South West should be tested independently before use as drinking water. Water Corporation's public water quality data does not cover private bores.
If you're on a private bore in the South West, do not assume the water is safe to drink without testing. Shallow bores near wetlands, agricultural land, or coastal areas can have iron bacteria, elevated nitrates, or coliform contamination. NATA-accredited laboratory testing costs $150–$400 for a comprehensive drinking water panel.
How South West water compares to Perth
This is a question many South West residents who have moved from Perth ask — and the answer is that South West scheme water is generally significantly better for most quality indicators:
- Hardness: South West towns range from 40–120 mg/L compared to Perth's 100–300+ mg/L. Most South West towns are notably softer.
- TDS: Much lower in surface water-supplied towns like Margaret River and Manjimup compared to Perth's groundwater and desalination blend.
- Chlorine: Similar approach — all schemes use chlorine disinfection. Levels vary by distance from treatment plants.
- Desalination: The South West does not rely on desalination the way Perth does. Surface water from forested catchments dominates.
The practical implication: whole-home TAC systems and softeners that are well-justified for Perth homeowners in Yanchep or Butler are often unnecessary for equivalent South West properties.
What filter makes sense for South West WA
The right answer depends on your specific town and water source:
- Bunbury (Aqwest): Carbon block for chlorine taste. TAC optional if you're seeing noticeable scale. Aqwest water is similar to a mid-range Perth suburb in hardness terms.
- Busselton/Dunsborough: Carbon block for taste. Hardness varies — check with Busselton Water for your zone.
- Margaret River/Augusta: Carbon block is usually sufficient. Softer water means scale is less of a concern. After-rain tannin — carbon block addresses this too.
- Manjimup/Pemberton: Basic carbon filtration if desired. Very soft water — no hardness treatment needed. Tannin after rain is the main aesthetic issue.
- Private bore water: Test first. Filtration requirements depend entirely on what the test finds — iron removal, UV for bacteria, or RO for broader treatment may all be relevant depending on results.
The South West's surface water-supplied towns (Margaret River, Manjimup) have genuinely soft, low-mineral water that requires minimal filtration. Bunbury and coastal plain groundwater areas are moderately soft — carbon block for taste is the primary need. Do not install Perth-grade hardness treatment systems without checking your specific town's data first.
Check your town's provider — Aqwest for Bunbury, Busselton Water for Busselton, Water Corporation for most other towns — and request their annual quality report. Use our comparison tool to evaluate suppliers independently before purchasing any system.