- →Metropolitan scheme water arsenic is well below the ADWG limit of 0.01 mg/L in all capital cities. Utilities treat for arsenic as part of standard water treatment. Metro residents do not need to test.
- !Private bore water in WA Goldfields, parts of SA and QLD, and areas near historical gold mines can have elevated natural arsenic. Test every 2–3 years if you use private groundwater in these regions.
- →The ADWG limit of 0.01 mg/L is a precautionary lifetime exposure limit. An occasional reading at or slightly above this is not equivalent to the high-exposure situations (50–500 µg/L) studied in epidemiological research.
- ✓Reverse osmosis (NSF 58) removes 85–95% of arsenate (As V) — the most common arsenic form in oxygenated groundwater. For arsenite (As III) in deep reducing aquifers, pre-oxidation significantly improves removal.
- ✗Standard carbon block filters do not remove arsenic. Neither does standard KDF media at residential flow rates. These are not arsenic treatment technologies.
Where arsenic comes from in Australian drinking water
Arsenic is a naturally occurring element found in the earth’s crust, primarily in sulphide mineral deposits. In surface and groundwater not affected by mineral deposits or industrial contamination, arsenic concentrations are generally below 0.005 mg/L — well within the ADWG health limit of 0.01 mg/L. The problem arises in specific geological and land-use contexts where arsenic is mobilised into groundwater at higher concentrations.
Sources of elevated arsenic in Australian water:
- Natural geological sources: Groundwater in areas with volcanic rocks, marine sediments, and certain sulphide-bearing formations can contain elevated arsenic. Parts of WA, SA and QLD have naturally elevated groundwater arsenic in specific hydrogeological zones.
- Gold mining drainage: Historical gold mining in Victoria, NSW, QLD and WA used arsenic compounds in processing and left arsenic-bearing tailings that can leach into surrounding groundwater over decades to centuries.
- Agricultural arsenic: Some older sheep dips used arsenic-based compounds. Legacy contamination from these sites persists in soil and groundwater in some rural areas.
- Industrial contamination: Smelting and metal processing operations in some regional areas.
For metropolitan scheme water supplies, SA Water explicitly confirms treatment processes to keep arsenic well below the ADWG health limit of 0.01 mg/L, as do Water Corporation (WA), Sydney Water and other utilities. The arsenic risk in Australia is concentrated in private groundwater in specific geological zones, not mains water.
The ADWG limit and the health basis
The Australian Drinking Water Guideline for arsenic is 0.01 mg/L (10 µg/L) — consistent with the WHO guideline. This is a health-based limit derived from epidemiological evidence, primarily from long-term exposure studies in Taiwan, Bangladesh, and other regions where natural groundwater arsenic is very high (50–500 µg/L). At these very high concentrations, arsenic causes:
- Skin lesions (keratosis, hyperpigmentation)
- Increased risk of skin, bladder, kidney and lung cancer
- Peripheral vascular disease
- Neurological effects in long-term, high-exposure populations
The evidence base for health effects at concentrations below 50 µg/L is much less clear. The 10 µg/L guideline represents a precautionary limit based on what is analytically achievable and is designed to minimise risk from lifetime exposure. An occasional reading at or slightly above this limit is not equivalent to the high-exposure situations studied in the epidemiological literature.
Higher-risk areas in Australia
While a comprehensive national arsenic mapping program has not been published, the following regions and contexts are associated with higher groundwater arsenic risk in Australia:
- Western Australia: Parts of the Goldfields, Pilbara and some coastal plain areas. Gold mining legacy sites near Kalgoorlie and other historical mining regions. WA DWER (Department of Water and Environmental Regulation) maintains groundwater quality databases.
- South Australia: SA Water treats for arsenic, confirming its natural presence in some source waters. Regional groundwater in the Far North and parts of the Murray Basin warrants testing for bore water users.
- Queensland: Historical mining areas in Central Queensland and Mount Isa region. Some agricultural bore water in the Channel Country.
- Northern Territory: Remote community water supplies have historically been a focus area for arsenic monitoring, particularly in areas with uranium and other mineral deposits.
For regional and remote Australia, a 2022 npj Clean Water study found arsenic and fluoride exceedances represented significant proportions of water quality failures in Indigenous communities and remote water schemes, highlighting the need for more comprehensive national monitoring.
Who should test for arsenic
Testing is warranted if you:
- Use private bore water in any of the high-risk regions listed above
- Live near a historical gold mine, smelter, or sheep dip site
- Use tank water on a property with old corrugated iron roofing (arsenic was historically used in some treatments and pigments, though the risk from modern iron roofing is much lower)
- Are in a remote community with a small water scheme that does not have full treatment documentation
NATA-accredited arsenic testing typically costs $40–$80 as a standalone test. A comprehensive heavy metals panel including arsenic, lead, manganese and copper costs $100–$200. Test every 2–3 years for stable private supplies, annually if near a known contamination source.
What removes arsenic
| Technology | Arsenic removal | Notes |
|---|---|---|
| Reverse osmosis (NSF 58) | 85–95% (As V) / 50–70% (As III) | Most effective residential technology for arsenate (As V). pH affects performance. RO combined with pre-oxidation achieves higher removal. |
| Activated alumina (NSF 53) | Up to 95% (As V) | Effective at pH 5.5–7.0. Saturates over time — requires frequent cartridge replacement. Best at point-of-use under-sink scale. |
| Iron oxide/ferric media | 80–95% | Common in WA bore water iron removal systems. Removes arsenic as a co-benefit. Requires backwash management. |
| Distillation | ~99% | Impractical for household volumes. |
| Standard carbon block | 0–5% — negligible | Carbon does not adsorb arsenate or arsenite effectively at residential flow rates. |
| Standard KDF media | Partial — inconsistent | Designed for chlorine and heavy metals. Not a reliable arsenic treatment at residential flow rates. |
Arsenic speciation matters: Arsenic exists in two main forms in groundwater — arsenate (As V, oxidised) and arsenite (As III, reduced). RO and activated alumina are significantly more effective against As V. In reducing groundwater conditions (deep bores, low oxygen), As III predominates and pre-oxidation (with chlorine or aeration) converts it to As V before filtration, substantially improving removal. If your water testing shows arsenic in a deep bore, ask your laboratory whether it can speciate the arsenic (As III vs As V) — this affects which treatment is most effective.
Metro scheme water arsenic is well managed by utilities. The risk is for private bore water users in mining-legacy areas, certain WA Goldfields and SA regions, and remote communities on small schemes. Testing is the starting point.
If arsenic is detected above 5 µg/L in a bore used for drinking, an NSF 58-certified RO system is the most practical residential treatment. For WA bore water systems with both iron and arsenic, an iron removal filter upstream of RO both protects the membrane and provides co-benefit arsenic removal. Use our bore water filtration guide for the full treatment approach.