Australian water quality — news and updates

The National Health and Medical Research Council (NHMRC) updated the Australian Drinking Water Guidelines (ADWG) in June 2025 with significantly lower PFAS guideline values, following accumulating evidence on health effects and in line with revisions by the US EPA and WHO. The June 2025 ADWG now sets individual health guideline values for specific PFAS compounds substantially below the previous single combined limit.

All major utility-supplied water in Australia that was previously compliant has been assessed against the new limits. Blue Mountains (Sydney Cascade catchment) was already undergoing GAC treatment installed December 2024. Households near known PFAS contamination sites — RAAF Williamtown, Oakey, Tindal, Edinburgh, and certain airport sites — should check with their local water authority for updated testing data.

Filter implication: Reverse osmosis (NSF 58 certified) removes 90–96% of PFAS and remains the most practical household intervention for those seeking additional protection beyond updated utility treatment.

Brisbane experienced its annual summer taste event in January 2025 driven by elevated Methylisoborneol (MIB) and Geosmin concentrations from blue-green algal blooms in Wivenhoe and Somerset dams. These compounds cause the distinctive earthy, musty or “dirt” taste that returns to Brisbane tap water each summer — most noticeably January to March and again May to July.

Seqwater confirmed the water remained safe to drink throughout the event. MIB and Geosmin are non-toxic taste compounds produced by naturally occurring Actinobacteria and cyanobacteria during warm water conditions. They are detectable by human taste receptors at very low concentrations (around 5–10 ng/L).

Filter implication: Activated carbon (GAC or carbon block) provides partial MIB/Geosmin reduction. For complete removal during acute taste events, reverse osmosis is the most effective household option. Advanced whole-home carbon systems with high contact time also reduce these compounds significantly.

Water Corporation confirmed Stage 2 of the Southern Seawater Desalination Plant (SSDP) expansion reached full operational capacity in early 2025, contributing an additional 50 GL/year to Perth’s supply mix. This increases the proportion of desalinated water in the Perth supply blend, which has opposing effects on different parameters: desalinated water has lower TDS and hardness than groundwater, but blending ratios vary significantly by zone and season.

Perth households in southern zones (Rockingham, Baldivis, Mandurah) and inner zones may experience lower hardness readings at certain times of year as the desal contribution to their supply zone increases. Northern zones (Yanchep, Butler, Wanneroo) remain predominantly groundwater-sourced and continue to see the highest hardness readings in Perth.

Filter implication: Perth hardness data from our suburb lookup reflects Water Corporation 2023–24 annual report averages. Actual current hardness may vary by zone and season as the desal/groundwater blend ratio changes. If you want a current reading, a TDS meter or hardness test strip gives an instant indication.

Sydney Water completed installation of emergency Granular Activated Carbon (GAC) treatment at Cascade Water Filtration Plant in December 2024, following PFAS detection in the Blue Mountains supply catchment that was reported publicly in June 2024. Testing in mid-2024 found PFAS compounds in Cascade WFP supply water. Subsequent monitoring and treatment have reduced concentrations to below the updated June 2025 ADWG limits.

Blue Mountains supply area covers Katoomba, Leura, Blackheath, Hazelbrook, Lawson, Wentworth Falls, Woodford, and Mount Victoria. Residents in these areas were supplied with bottled water during the interim period.

Filter implication: Current Blue Mountains tap water meets updated ADWG PFAS limits as of the June 2025 revision. Households seeking additional certainty beyond utility treatment: RO (NSF 58) removes 90–96% of PFAS. The Cascade zone is flagged in our Sydney suburb lookup tool.

The International Agency for Research on Cancer (IARC), the cancer research arm of the WHO, classified PFOA (perfluorooctanoic acid) as a Group 1 carcinogen in June 2024 — the highest classification, meaning there is sufficient evidence of carcinogenicity in humans. PFOS (perfluorooctane sulfonate) was classified as Group 2B (possibly carcinogenic). These classifications informed the subsequent ADWG guideline revisions in June 2025.

The IARC classification reflects the accumulation of epidemiological and mechanistic evidence since PFAS first emerged as a public health concern in Australian drinking water around 2016. It does not mean current tap water levels are dangerous — guidelines set safe exposure limits with significant margins below levels associated with harm. It does reinforce the precautionary approach of reducing PFAS exposure where practical.

A pre-summer MIB/Geosmin event was reported in Brisbane in December 2024 as warming reservoir temperatures triggered early algal activity in Wivenhoe Dam. Residents in inner Brisbane zones (highest hardness, sourced via Mt Crosby WTP from Wivenhoe) reported the characteristic earthy/musty taste returning to tap water from mid-December.

Seqwater’s powdered activated carbon (PAC) dosing — which is activated when MIB/Geosmin concentrations exceed taste thresholds — was deployed during the event. Despite this treatment, MIB at very low concentrations remains detectable by many people. The events are expected to continue as a seasonal pattern.

Trend note: Brisbane taste events have become more frequent and intense in recent years, correlated with increasing reservoir temperatures. Households in Brisbane who want consistent taste without seasonal variation may consider an under-sink RO system — which removes MIB/Geosmin as completely as any household technology.