Blue Mountains tap water currently meets Australian Drinking Water Guidelines at the tap. But the ongoing PFAS investigation in the upper catchment — and what the raw water data actually shows — is something every household between Springwood and Blackheath deserves to understand clearly.
The Short Answer
Yes, Blue Mountains tap water is within Australian Drinking Water Guidelines at the point it reaches your tap. Sydney Water and NSW Health have confirmed this consistently since the PFAS issue became public in June 2024, and a dedicated treatment system has been operating at the Cascade Water Filtration Plant since January 2025.
But the full picture is more complex than that single statement. The source water feeding into the Cascade plant still contains elevated PFAS. Two contaminated dams remain disconnected from supply indefinitely. A detailed site investigation is underway and won't be complete for around 12 months. And the National Health and Medical Research Council (NHMRC) updated its PFAS guidelines in June 2025 with lower recommended values — meaning what was previously "within guidelines" now occupies a narrower margin.
Blue Mountains residents deserve the full picture. Here it is.
Where Blue Mountains Water Comes From
The Blue Mountains is supplied by Sydney Water's Cascade Water Filtration Plant, located at Katoomba. The plant treats water from a network of five dams in the upper Blue Mountains catchment: Medlow Dam, Greaves Creek Dam, and Upper, Middle, and Lower Cascade Dams.
The system can also draw on the Oberon pipeline — part of the Fish River Scheme — which brings water from Oberon Dam on the western side of the Great Dividing Range. This Oberon-sourced water tests effectively clean for PFAS and is an important backstop for the Blue Mountains supply.
Approximately 41,000 homes across the middle and upper Blue Mountains are supplied from the Cascade plant, covering areas including Katoomba, Leura, Wentworth Falls, Blackheath, Mount Victoria, Woodford, Lawson, and Catalina.
The PFAS Issue: What Happened and Where Things Stand
June 2024: Detection and public disclosure
In June 2024, Sydney Water detected elevated PFAS levels at the outlet of the Cascade Water Filtration Plant. Public disclosure followed, along with confirmation that communities in the Blue Mountains had likely been drinking water with elevated PFAS for an extended period — potentially decades — without knowing it.
PFAS — per- and polyfluoroalkyl substances — are "forever chemicals" that don't break down in the environment or the human body. They accumulate over time and are associated with a range of health effects at sufficient exposure levels. The source of the contamination in the Blue Mountains was subsequently identified as firefighting foam (AFFF — aqueous film-forming foam) used in two separate motor vehicle accidents on the Great Western Highway (in 1992 and 2002) near Medlow Bath, and the Medlow Bath Rural Fire Brigade station.
The treatment response
The NSW Government installed a $3.5 million mobile water treatment system at the Cascade Water Filtration Plant, operational since January 2025. The treatment uses two of the most effective PFAS-removal methods available: granular activated carbon (GAC) and ion exchange resin — which work by adsorbing PFAS compounds as water passes through, removing them before the water enters the distribution network.
A permanent $80–$100 million upgrade to the Cascade plant has been committed by the NSW Government, expected to be operational by 2026–2027.
What the raw water data shows right now
WaterNSW publishes monthly raw water monitoring results for the Blue Mountains dam network. The most recent data (July 2026) is unambiguous: Medlow Dam and Greaves Creek Dam still contain significantly elevated PFAS.
| Source | PFOS (µg/L) — July 2026 raw water | ADWG guideline (8 ppt = 0.008 µg/L) | Status |
|---|---|---|---|
| Greaves Creek Dam | 0.0377 µg/L (37.7 ppt) | 0.008 µg/L (8 ppt) | ~4.7× above guideline — DISCONNECTED from supply |
| Medlow Dam | 0.0478 µg/L (47.8 ppt) | 0.008 µg/L (8 ppt) | ~6× above guideline — DISCONNECTED from supply |
| Upper Cascade Dam | 0.0010 µg/L (1.0 ppt) | 0.008 µg/L (8 ppt) | Within guideline |
| Source water inlet to Cascade WFP | 0.0009 µg/L (0.9 ppt) | 0.008 µg/L (8 ppt) | Within guideline — treated further at plant |
| Oberon pipeline (backup supply) | <0.0003 µg/L (non-detect) | 0.008 µg/L (8 ppt) | Effectively clean |
Source: WaterNSW Blue Mountains PFAS monitoring, July 2026. Raw (untreated) water only — these figures are not the tap water figures.
The critical point: Medlow and Greaves Creek Dams are permanently disconnected from supply while the investigation continues and will only be reconnected once appropriate permanent mitigation is in place. WaterNSW has been explicit that this may not happen for an extended period.
The water actually entering the Cascade treatment plant comes primarily from the Upper Cascade Dam system and the Oberon pipeline — both within guidelines before treatment. After treatment with the GAC and ion exchange resin system, PFAS levels in the treated drinking water are further reduced. Tap water results (from Sydney Water's quarterly monitoring) have been reported within ADWG guidelines.
The Updated Guidelines: A Narrower Margin
In June 2025, the NHMRC released updated Australian Drinking Water Guidelines with new, lower recommended values for PFAS in drinking water — reflecting the latest toxicological evidence and aligning more closely with international standards that have been progressively tightened in recent years.
This matters for Blue Mountains residents because "within the previous guidelines" now describes a larger margin than "within the current guidelines." The treatment system and monitoring program are designed around current standards, but the fact that guidelines were updated in 2025 reflects ongoing scientific understanding that PFAS pose greater risk at lower concentrations than was previously understood.
For households that want to go beyond regulatory compliance — particularly those with young children, pregnant women, or anyone who has been a long-term resident — point-of-use filtration provides an additional layer of assurance regardless of what the compliance data shows.
The Ongoing Investigation
A full Detailed Site Investigation (DSI) of the Upper Blue Mountains Drinking Water Catchment is currently underway, led by independent environmental consultant ERM and overseen by WaterNSW, the EPA, NSW Rural Fire Service, Transport for NSW, and other agencies. The DSI will include soil, groundwater, surface water, and sediment analysis across potential source areas.
Key points about where the investigation stands:
- The DSI will take approximately 12 months to complete from commencement
- Findings will guide a PFAS Management Plan for long-term mitigation
- Medlow Dam and Greaves Creek Dam will remain disconnected from supply until the investigation is complete and permanent mitigation is in place
- WaterNSW continues to publish raw water monitoring data monthly
The investigation is thorough and transparent. But it means the Blue Mountains PFAS situation is not resolved — it is being actively managed, with a treatment system bridging the gap while the long-term solution is developed.
The Rest of Your Water: Fluoride, Chlorine, and Hardness
Beyond PFAS, Blue Mountains tap water (Katoomba data) shows:
| Parameter | Blue Mountains level | ADWG guideline | Status |
|---|---|---|---|
| Fluoride | 1.04 mg/L | 1.5 mg/L | Within guideline |
| Chlorine | 1.06 mg/L | 5 mg/L | Within guideline — noticeable taste |
| PFAS (treated tap water) | Below 8 ppt (ADWG) | 8 ppt | Within current guideline — monitoring ongoing |
| pH | Adjusted to 7.0–8.0 | 6.5–8.5 | Within range |
The chlorine level at 1.06 mg/L is notably higher than typical inner-Sydney levels — longer pipe runs in mountain terrain require a stronger residual to maintain disinfection at the tap. This contributes to a more noticeable chlorine taste in Blue Mountains tap water compared to metropolitan Sydney.
What Point-of-Use Filtration Can Do
This is where the story becomes directly relevant to what you can do at home.
The treatment system installed at Cascade WFP uses granular activated carbon and ion exchange resin — the two methods that authorities and scientists identify as most effective for PFAS removal from drinking water. This is not coincidental: these are the proven tools for the job.
Genzon's 5-stage gravity purifier includes both of these in its Stage 2 multi-media cartridge: activated carbon (for chlorine, chloramines, VOCs, and PFAS adsorption) and ion exchange resin (for heavy metals and further PFAS reduction). In other words, the same filtration chemistry the NSW Government deployed in its emergency treatment response is part of Genzon's standard purification process — at the household level, at the point of use.
Beyond PFAS, Genzon's 5 stages additionally provide:
- 0.2-micron ceramic pre-filter — removes bacteria, sediment, and particulates at the source
- Deep-sea mineral stones — restores calcium, magnesium, and potassium; raises pH to naturally alkaline 7.5–9.0
- Colloidal silver stage — antimicrobial protection for water stored in the lower chamber
- Magnetic ionisation tap — 1,200 gauss, providing a final antimicrobial barrier and ionised water at the point of dispense
No electricity. No plumbing. No water waste.
Should Blue Mountains Residents Filter Their Water?
The regulatory answer is: your tap water is within guidelines and is safe. NSW Health's position is consistent on this.
The practical answer, for households that want to go beyond regulatory minimums, is that point-of-use filtration using activated carbon and ion exchange resin provides additional PFAS reduction at the tap — on top of what the treatment plant is already doing. This is particularly relevant for:
- Households with infants or young children
- Pregnant or breastfeeding women
- Long-term residents who may have had higher historical exposure before treatment was installed
- Anyone who prefers to take a precautionary approach while the investigation is ongoing
Even if PFAS is your only concern, the additional benefits of a 5-stage gravity purifier — mineralisation, chlorine removal, bacteria protection — make it a meaningful upgrade over unfiltered tap water for any Blue Mountains household.
And at under $0.10 per litre to run, it costs less per day than a bottle of water from the service station.
Frequently Asked Questions
Is Blue Mountains tap water safe to drink in 2026?
According to Sydney Water and NSW Health, yes — treated tap water in the Blue Mountains meets Australian Drinking Water Guidelines. A PFAS treatment system has been operating at the Cascade Water Filtration Plant since January 2025, and treated drinking water results are within current ADWG values. The situation is being actively managed, with an ongoing detailed site investigation and a permanent plant upgrade committed for 2026–2027.
Which Blue Mountains areas are affected by the PFAS issue?
The Cascade Water Filtration Plant supplies the middle and upper Blue Mountains, including Katoomba, Leura, Wentworth Falls, Blackheath, Mount Victoria, Woodford, Lawson, and Catalina — approximately 41,000 homes. Lower Blue Mountains areas (Springwood, Penrith) are supplied by different treatment plants and are not part of the Cascade PFAS issue.
Are the contaminated dams still connected to the water supply?
No. Medlow Dam and Greaves Creek Dam — which contain PFOS at levels significantly above guidelines in their raw water (37–48 ppt vs the 8 ppt guideline as of July 2026) — have been permanently disconnected from supply. They will only be reconnected once the detailed site investigation is complete and appropriate permanent mitigation is in place.
What is the PFAS source in the Blue Mountains catchment?
WaterNSW's initial investigation identified three probable sources: two separate motor vehicle accidents on the Great Western Highway near Medlow Bath (in 1992 and 2002) that involved firefighting foam (AFFF — aqueous film-forming foam containing PFAS), and the Medlow Bath Rural Fire Brigade station. PFAS from these sources has migrated into the Adams Creek catchment and downstream into Medlow and Greaves Creek Dams over time.
Does a gravity water filter help with PFAS?
Yes. Activated carbon and ion exchange resin — both present in Genzon's Stage 2 multi-media cartridge — are the same filtration methods used in the treatment system installed at the Cascade plant by the NSW Government. At the household level, point-of-use filtration provides additional PFAS reduction on top of what the treatment plant does, as well as addressing chlorine, heavy metals, and other contaminants.
What's the timeline for a permanent fix?
The NSW Government has committed $80–$100 million to a permanent upgrade of the Cascade Water Filtration Plant, expected to be operational by 2026–2027. The detailed site investigation of the contamination source is expected to take approximately 12 months to complete. WaterNSW publishes monthly raw water monitoring results at waternsw.com.au.
Blue Mountains residents deserve water they don't have to think twice about. Genzon's 5-stage gravity purifier — using the same activated carbon and ion exchange chemistry as the NSW Government's treatment response — gives you that at the point of use.
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Data sourced from WaterNSW Blue Mountains PFAS monitoring (published monthly), Sydney Water PFAS and drinking water information, and NSW Government media releases. Raw water figures are untreated source water and are not the same as treated tap water. Current to July 2026. For the latest treated drinking water results, visit sydneywater.com.au. For raw water monitoring updates, visit waternsw.com.au/water-services/water-quality/pfas/blue-mountains-investigations.