Australian Tap Water:
What’s In It and What You Should Know
Updated August 2026
Australian tap water is generally considered safe to drink, and regulated water suppliers routinely test and treat drinking water against the Australian Drinking Water Guidelines.
But “safe” does not mean our water contains nothing except H₂O.
Our understanding of water quality is constantly changing as laboratory testing becomes more sensitive and scientists begin looking for chemicals that were rarely measured in the past.
Recent investigations into PFAS contamination in the Blue Mountains, new research identifying a much wider range of PFAS compounds in Sydney tap water, and Australian studies detecting PFAS in rainfall all highlight an important point:
What enters our drinking-water catchments is changing — and our testing and treatment systems need to keep evolving with it.
This isn't a reason to panic or stop drinking tap water. It is a reason to understand where our water comes from, what can enter it, and what happens between the catchment and the glass on your kitchen bench.
The Blue Mountains PFAS Discovery
One of the clearest recent examples comes from Medlow Bath in the Blue Mountains of NSW.
Testing found elevated PFAS levels in Medlow Dam, part of the catchment supplying the Cascade Water Filtration Plant. WaterNSW subsequently disconnected Medlow Dam and Greaves Creek Dam from the supply system while investigations continued.
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What makes the case particularly important is where the contamination may have come from.
WaterNSW's investigation identified three potential historical sources: two motor vehicle accident sites on the Great Western Highway dating from 1992 and 2002, and the Medlow Bath Rural Fire Brigade station.
The PFAS chemical signature found in the area was consistent with the historical use of aqueous film-forming firefighting foam, or AFFF. WaterNSW says contamination may have travelled through the catchment via rainfall, surface-water runoff and previous water transfers between dams.
That means an event that happened decades ago may still be influencing the chemistry of a drinking-water catchment today.
As of March 2026, a detailed investigation involving soil, groundwater, surface water and sediment testing was continuing. Medlow and Greaves Creek dams remained disconnected from the supply network. Water from Oberon Dam was being used to reduce PFAS concentrations, and dedicated PFAS treatment has been operating at the Cascade plant since December 2024. NSW Health and Sydney Water advise that the drinking water currently supplied to the Blue Mountains complies with Australian Drinking Water Guidelines and is safe to drink.
That distinction matters.
Contamination in a catchment does not automatically mean unsafe water is coming from the tap. Water treatment, blending, monitoring and removing affected sources from service are all parts of the protection system.
But Medlow Bath shows why proactive testing matters.
What Exactly Are PFAS?
PFAS — per- and polyfluoroalkyl substances — are a very large family of synthetic chemicals that have been used in products such as firefighting foams, waterproof and stain-resistant materials, industrial processes and some consumer products.
They are commonly called “forever chemicals” because many PFAS compounds break down extremely slowly and can remain in soil, water and the wider environment for many years.
As scientific evidence has developed, Australian guidelines have also changed.
In June 2025 the National Health and Medical Research Council updated Australia's drinking-water guideline values to:
PFOS: 8 nanograms per litre • PFHxS: 30 ng/L • PFOA: 200 ng/L • PFBS: 1,000 ng/L.
These extraordinarily small numbers illustrate how sensitive modern chemical testing has become.
We're Finding More Because We're Looking for More
Another important development came from researchers at UNSW Sydney.
Researchers analysing samples collected from Sydney's drinking-water catchments identified 31 different PFAS compounds in tap water, including 21 that had not previously been reported in Australian tap water.
Importantly, the concentrations were low and Sydney's water continued to meet current Australian drinking-water standards.
But the study highlighted a challenge for regulators: scientists can now detect a much wider range of PFAS chemicals than the handful for which specific Australian drinking-water guideline values currently exist.
That doesn't mean these newly detected compounds are automatically dangerous at the concentrations found.
It means our ability to detect chemicals is moving faster than our ability to fully understand every compound and establish individual health guidelines for it.
This is one reason ongoing monitoring is so important.
The NSW parliamentary inquiry into PFAS contamination also concluded in 2025 that Sydney Water had not undertaken an appropriate level of due diligence before previously stating that there were no known PFAS hotspots within Sydney's drinking-water catchments.
The lesson isn't that Australian tap water cannot be trusted.
The lesson is that testing needs to keep evolving.
Can Chemicals Actually Arrive in Rain?
This is perhaps one of the most surprising developments.
We often imagine rain falling into a protected forest catchment as essentially pure water.
Unfortunately, the modern environment is more complicated.
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A 2026 Australian study analysed rainfall collected near Melbourne and detected eight of the 30 PFAS compounds tested for. Total measured PFAS concentrations varied substantially between samples.
The researchers stressed that it was a small study and not a comprehensive survey of Australian rainfall. The samples also remained within Australia's current PFOS and PFOA drinking-water guideline values.
However, the research demonstrated something important: atmospheric transport and rainfall can be a pathway by which persistent synthetic chemicals return to the land and waterways. The authors concluded rainfall could potentially represent a meaningful source of PFAS entering Australian water bodies.
So contaminants do not necessarily need to be dumped directly into a dam.
Chemicals released through decades of industrial activity and consumer use can move through soil, dust, waterways and the atmosphere before eventually entering rivers, dams and catchments.
This doesn't mean every rainfall event is contaminating your drinking water at dangerous levels.
It does mean the old idea that a remote or bushland catchment is completely isolated from modern chemical pollution is becoming harder to maintain.
Water Can Also Change After It Leaves the Treatment Plant
The catchment is only one part of the story.
After treatment, water may travel many kilometres through reservoirs, mains, service pipes and finally the plumbing inside your home.
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Australian water suppliers routinely monitor public drinking water, but the water supplier's network generally ends at the property's point of supply.
From there, household plumbing can influence the water that ultimately reaches your glass.
Lead is a good example.
Australia does not commonly have the extensive lead water-service pipe networks found in some older overseas cities. However, the NHMRC says lead can still be present in plumbing products including some brass and copper-alloy fittings, where small amounts can leach into water.
In 2025 Australia's health-based drinking-water guideline for lead was reduced from 0.01 mg/L to 0.005 mg/L.
And from 1 May 2026, new plumbing installations carrying drinking water must use compliant Lead Free WaterMark products for relevant copper-alloy components, with a weighted average lead content of no more than 0.25%.
That is a significant change.
It also illustrates why water quality shouldn't only be considered at the treatment plant.
Older homes, ageing fittings, corrosion, stagnant water and the materials used within a building can all influence the water at the final tap.
This doesn't mean every old pipe — or every plastic pipe or fitting — is dangerous. Plumbing materials and their risks vary enormously.
But if you live in an older property, have unknown plumbing materials, notice metallic tastes or discolouration, or simply want to know what is coming from your own tap, testing the water at the point of use provides much more useful information than assuming the water leaving the treatment plant is identical to the water reaching your kitchen.
NHMRC also notes that flushing taps after extended periods of non-use can help reduce exposure to metals that may have leached from plumbing products.
PFAS Isn't the Only Thing We Monitor
PFAS attracts attention because it is persistent and our understanding of it is still developing, but Australian drinking water can contain many other substances at varying concentrations.
These can include naturally occurring minerals and metals, chlorine or chloramine used for disinfection, treatment by-products, sediment, agricultural chemicals, industrial chemicals and contaminants associated with local geology or land use.
Different regions can therefore have very different water-quality challenges.
For example, elevated manganese levels reported in some remote Northern Territory drinking-water supplies prompted the NHMRC to review its national guidance.
The important concept is concentration.
Detecting a chemical does not automatically mean the water is harmful.
Modern laboratories can measure substances at parts per billion and even parts per trillion. What matters is what has been detected, how much is present, how frequently people are exposed and what the scientific evidence says about that exposure.
Why Filter Tap Water If It Meets Drinking-Water Guidelines?
Choosing a water filter doesn’t have to mean your tap water is unsafe. For some households, it’s simply about improving taste and odour so drinking water is more enjoyable.
Others want to reduce a particular substance identified in their local water-quality report or through testing at home. The right choice depends on your water supply, household plumbing and what you want to achieve.
There is also the question of emerging contaminants. As the PFAS examples above illustrate, contamination can exist long before it is identified or fully understood, and drinking-water guidelines evolve as scientific evidence develops. This does not mean water meeting current guidelines is necessarily harmful, but it helps explain why some households choose additional filtration as a precaution—provided the filter has demonstrated performance against the substances they want to reduce.
What Can You Do About Your Drinking Water?
For most Australians, there is no reason to suddenly stop drinking tap water.
But if you want greater control over what you and your family drink, there are some sensible steps you can take:
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Check your local water-quality report. Water utilities publish monitoring information and this can tell you far more about your local supply than national averages.
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Test where necessary. If you have older plumbing, tank water, bore water or a specific contamination concern, consider testing through a NATA-accredited laboratory.
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Choose filtration for the contaminant you're concerned about. Activated carbon, specialist adsorption media and reverse osmosis all work differently. No single filter removes absolutely everything, and PFAS, fluoride, lead, chlorine and other contaminants require different approaches. Look for independent laboratory testing that specifically supports the contaminant-reduction claims being made for the filter you choose.
Awareness, Not Alarm
Australia is fortunate to have sophisticated drinking-water treatment and monitoring systems.
The recent PFAS discoveries don't change that.
What they do show is that the chemical environment around us has become increasingly complex.
A firefighting foam used beside a road decades ago can leave a chemical legacy. Contaminants can travel through groundwater and surface runoff. Some persistent chemicals can even move through the atmosphere and return in rainfall. And once treated water reaches our property, the plumbing inside the building can change it again.
At the same time, laboratory technology is improving rapidly, allowing scientists to detect compounds at concentrations that would have been impossible to measure only a generation ago.
For us, the sensible response isn't fear.
It's awareness.
Know where your water comes from. Look at the evidence. Understand the contaminants that are relevant to your area. And if you choose to filter your drinking water, choose a system because its filtration technology and independent testing match what you actually want to reduce — not because of frightening marketing claims.
That's ultimately what better water quality is about: being informed enough to make your own decision about the water you drink every day.
Sources and Further Reading
1. Blue Mountains PFAS Investigation — WaterNSW
Official information about WaterNSW’s investigation into PFAS detected in the Blue Mountains catchment, including monitoring, potential historical sources and the continuing detailed investigation.
View the WaterNSW investigation →
2. Initial Blue Mountains Investigation Findings — WaterNSW
WaterNSW’s May 2025 findings identifying three potential historical PFAS sources near Medlow Bath and evidence consistent with the historical use of aqueous film-forming firefighting foam.
Read the initial investigation findings →
3. PFAS and Drinking-Water Updates — NSW Government
Current NSW Government information about PFAS monitoring, drinking-water compliance and the detailed investigation into contamination in the Upper Blue Mountains drinking-water catchment.
View NSW Government information and updates →
4. PFAS and Drinking Water — Sydney Water
Information about PFAS monitoring across Sydney Water’s filtration plants and the purpose-built treatment system operating at the Cascade Water Filtration Plant.
View Sydney Water’s PFAS information →
5. Updated Australian Drinking Water Guidelines — NHMRC
The National Health and Medical Research Council’s June 2025 update establishing revised Australian health-based guideline values for PFOS, PFHxS, PFOA and PFBS in drinking water.
Read the NHMRC guideline update →
6. PFAS Identified in Sydney Tap Water — UNSW Sydney
A summary of UNSW research identifying 31 types of PFAS in sampled Sydney tap water, including 21 compounds not previously reported in Australian tap water. The researchers emphasise the need for broader monitoring while noting that measured concentrations were low.
Read the UNSW research summary →
7. PFAS in South-Eastern Australian Rainwater — Environmental Toxicology and Chemistry
A peer-reviewed Australian study published in July 2026 examining PFAS in south-eastern Australian rainwater. Eight of the 30 compounds tested for were detected, demonstrating that atmospheric transport and rainfall can contribute to PFAS entering land and water bodies.
Read the peer-reviewed study →
8. Lead and Other Metals from Plumbing Products — NHMRC
Official guidance explaining how lead and other metals may leach from plumbing products into drinking water. It also covers Australia’s Lead Free WaterMark requirements for relevant new plumbing installations from 1 May 2026.
Read the NHMRC plumbing-products guidance →
9. Australian Drinking-Water Guideline for Lead — NHMRC
The current Australian health-based guideline for lead in drinking water, including information about household plumbing as a potential source of lead after water leaves the treatment and distribution network.
View the NHMRC lead guideline →
10. NSW Parliamentary Inquiry into PFAS Contamination
The NSW Parliament Select Committee inquiry into PFAS contamination in waterways and drinking-water supplies throughout New South Wales. The inquiry’s final report was tabled on 11 September 2025, followed by the NSW Government’s response.