How Water Quality Varies Across Australia — State by State
By Sam Mendez — Chartered Process Engineer (CPEng), Engineers Australia
One of the most common misconceptions about Australian water is that it’s uniform. It isn’t. The water that comes out of a tap in Melbourne is chemically different from the water in Brisbane, which is different again from what a household in rural South Australia or the Northern Territory receives. And if you’re on a rainwater harvesting system, you’re dealing with a different set of considerations entirely.
Understanding your local water is the first step to understanding what — if anything — you want to filter.
Victoria and Metropolitan Melbourne
Melbourne’s water is sourced primarily from protected catchments in the Yarra Ranges — some of the cleanest source water in the world. Because the catchments are protected from human activity, the source water requires relatively minimal treatment before it’s safe to distribute.
Melbourne Water switched from chlorine to chloramine as the primary residual disinfectant during the 2000s and 2010s. This means Melbourne’s water has lower trihalomethane levels than cities that use free chlorine, but contains residual monochloramine — a compound that requires catalytic activated carbon (such as catalytic GAC) to remove effectively, rather than standard carbon.
Water hardness in Melbourne is relatively low — around 10–50 mg/L as calcium carbonate — making scale buildup in taps and appliances much less of an issue than in other parts of Australia. However, hardness varies across the distribution network.
What to filter for in Melbourne: Residual taste and odour. Note that Melbourne uses chloramine, which shower and tap filters reduce less effectively than free chlorine.
New South Wales and Sydney
Sydney’s water comes primarily from a series of dams — Warragamba, Shoalhaven, and others — fed by rainfall in the Blue Mountains catchment. It’s treated at the Prospect and Orchard Hills water filtration plants, among others.
Sydney Water uses free chlorine as its primary disinfectant (with chloramine used in parts of the network), and fluoride is added at around 1.0 mg/L. The water is moderately hard by Australian standards, around 50–100 mg/L depending on the zone.
Customers on the edges of the Sydney network — particularly in areas drawing from the Shoalhaven system — can experience greater variability in taste and odour, as the longer distribution distances mean higher residual disinfectant levels are maintained to ensure safety throughout the network.
What to filter for in Sydney: Free chlorine and sediment (in older properties).
Queensland
Queensland’s water supply is among the more complex in Australia, largely because of the South East Queensland water grid — a network linking multiple catchments, reservoirs, and treatment plants across a large region, including Wivenhoe Dam, Hinze Dam, and others.
QUU (Queensland Urban Utilities) and Unitywater treat and distribute water across the greater Brisbane and Sunshine Coast regions. Chloramine is used in parts of the network. Water hardness in Queensland varies significantly — from soft in some catchment areas to moderately hard in others.
Regional and remote Queensland is where supply systems diverge significantly. Many rural households rely on groundwater (bores) or rainwater harvesting, each with their own distinct chemistry profiles. Bore water can contain elevated iron, manganese, and hardness. Rainwater can be soft and slightly acidic, but may carry contamination from roof catchment surfaces and gutters.
What to filter for in Queensland: Chloramine or chlorine depending on zone; groundwater users should address iron, manganese, and hardness; rainwater users should address sediment, bacteria risk, and roof contamination.
South Australia
South Australia has the most variable and, in some regions, the most challenging water quality of any mainland state. Much of metropolitan Adelaide’s water is sourced from the River Murray — a river that has faced decades of agricultural runoff, salinity issues, and reduced flow.
SA Water has invested significantly in treatment infrastructure, but the source water characteristics mean that Adelaide tap water has higher salinity and mineral content than most other capital cities. Total dissolved solids (TDS) can be noticeably higher, contributing to the taste and flavour profile that Adelaide residents often comment on.
Desalination now contributes a portion of Adelaide’s supply via the Adelaide Desalination Plant at Port Stanvac. Desalinated water has very low TDS and is remineralised before distribution — the blend between Murray water and desalinated water varies seasonally.
What to filter for in South Australia: Chlorine residuals, elevated minerals and salinity, taste and odour from River Murray source water.
Western Australia
Perth’s water supply draws from multiple sources: surface water from the Darling Ranges, groundwater from the Gnangara and Jandakot mounds, and desalinated water from the Kwinana and Southern Seawater Desalination Plants. Desalination now supplies approximately half of Perth’s drinking water.
Water hardness in Perth varies significantly by source and suburb, but is generally higher than in Melbourne or Sydney — particularly in areas drawing from groundwater, where calcium and magnesium content can be substantial. Hard water is responsible for limescale buildup in kettles, taps, and shower screens — something Perth residents are very familiar with.
Chlorine is the primary disinfectant used in Perth’s distribution system.
What to filter for in Perth: Free chlorine, water hardness and scale, sediment.
Rainwater Harvesting Systems
A significant proportion of Australian households — particularly in rural and peri-urban areas — rely partly or wholly on rainwater harvested from rooftops. In Queensland, the ACT, and parts of South Australia, rainwater tanks are common even in urban fringe areas.
Rainwater is naturally soft and low in minerals, but it is not inherently safe. It can carry contamination from roofing materials (particularly older metal roofs with lead-based paint or lead flashing), bird and animal faeces, atmospheric pollutants, and organic debris in gutters.
Rainwater systems that aren’t maintained — gutters not cleaned, first-flush diverters not working, tank not cleaned — can develop bacterial contamination including E. coli.
Unlike municipal water, rainwater has no residual disinfectant. This is both an advantage (no chlorine) and a risk (no protection against biological contamination).
For rainwater users, filtration needs are fundamentally different from mains water users. Sediment filtration, activated carbon, and UV disinfection are typically required for a comprehensive solution. AQVO filters are specified for treated mains water; on a rainwater system, talk to a tank-water specialist about sediment, carbon and UV treatment first.
What to filter for on rainwater: Sediment, organic matter, roof contamination, biological risk (UV recommended for tank treatment).
The Common Thread
Whether you’re in metropolitan Melbourne on chloraminated mains water, in Adelaide on Murray River supply, or in rural Queensland on a bore or rainwater tank — the principle is the same. Your bulk water treatment, wherever it comes from, gets you most of the way there. Point-of-use filtration addresses what’s specific to you, your location, and your plumbing.
AQVO’s shower filter and tap filter are chosen for treated Australian mains water — chlorine, taste and odour — and we say plainly what they don’t do. If you’d like specific guidance on what’s most relevant for your situation, feel free to get in touch.