Water Quality Roundup: week of 21 September 2026
This week's roundup covers a precautionary boil water alert in Boulia, Queensland, disinfectant-related taste and odour complaints in south-west Sydney, continuing barium issues at Bulla in the Northern Territory, New Zealand's latest national drinking water regulation report and a Wairarapa boil water notice, and a short-lived E. coli advisory in the United States.
Australia & New Zealand
Guideline & regulatory updates
Taumata Arowai reports gains in protozoal treatment, but gaps remain
On 21 September 2026 the Water Services Authority – Taumata Arowai released its Drinking Water Regulation Report 2025. The report states that around 415,000 more people are now served by council supplies with protozoal treatment barriers than in 2023, and that 84% of New Zealanders receive water from registered suppliers. It also identifies 51 supplies serving 311,000 people that lacked a protozoal barrier at the end of 2025 (an updated figure after the reporting period is 112,336 people), and reports that only 45% of large council supplies met all distribution network requirements. The report signals the regulator's continuing focus on multiple-barrier treatment and distribution system integrity, supported in 2025 by four directions and its first prosecution for an alleged failure to supply safe drinking water.
Incidents
Precautionary boil water alert for Boulia, Queensland, after treatment plant communications outage
On 24 September 2026 Boulia Shire Council issued a precautionary boil water alert for all residents and visitors in Boulia, following a communications network outage that affected technical operations at the town's water treatment plant. The council stated that the supply was complying with water quality requirements, and that the alert will remain in place until it is satisfied levels are within the required range with consistent testing. Residents are advised to use boiled or bottled water for drinking and food preparation. The notice illustrates how loss of telemetry and control systems can lead a supplier to issue a precautionary advisory while normal monitoring is restored.
Source: Boulia Shire Council
Chlorine taste and odour complaints in south-west Sydney after disinfectant change
7NEWS reported this week that residents in Spring Farm, Mount Annan, Oran Park, Gregory Hills, Grasmere and Cobbity have complained of a strong chlorine smell in their tap water, with some residents reporting skin irritation. Sydney Water told 7NEWS it had switched disinfection in the area from monochloramine to free chlorine, which can produce a more noticeable taste and odour, and that chlorine is essential to keeping the water safe to drink. The report is a reminder of the customer communication challenges that can accompany changes in disinfection regime, even where the supply remains safe.
Source: 7NEWS
Barium above guideline value continues to affect Bulla, Northern Territory
Power and Water Corporation has reported that naturally occurring barium in the Bulla community's drinking water supply remains above the Australian Drinking Water Guidelines health value. In its Annual Drinking Water Quality Report 2025 release, Power and Water said it had begun supplying bottled water to Bulla residents as a temporary measure while it evaluates permanent solutions. The case highlights the difficulty of managing naturally occurring chemical exceedances in small remote groundwater supplies.
Source: Power and Water Corporation
Boil Water Notice for Ōpaki supply near Masterton after E. coli detections
On 25 September 2026 Taumata Arowai encouraged users of the Ōpaki Water Supply Association supply, in the Masterton District, to follow a Boil Water Notice issued after high levels of E. coli were detected. The Authority has directed that the notice remain in place until water quality is restored and that monitoring of the supply continue, and Masterton District Council has decommissioned a public tap in Lansdowne connected to the supply. The Authority advised anyone with gastrointestinal symptoms who has consumed water from the supply since the end of August to contact their healthcare provider or Healthline. The notice illustrates the Authority applying its direction powers to a supplier outside council ownership.
Viridis comment: Although some of these incidents are due to actual water quality concerns, others are precautionary and probably the result of implementing critical control point methodology whereby if a critical limit has been exceeded or it is uncertain that it has been exceeded control measures are implemented. This approach reduces the risk to consumers by taking full precaution where the safety of the water is uncertain.
There is also an important point that consumers can tell when there is a change in their water supply and it's important not to dismiss complaints. They are real-time monitoring. In the South-west Sydney case the cause of the change in water aesthetics was known.
International
Incidents
Precautionary E. coli boil water advisory in Jackson, Wyoming, lifted after clean retests
On 25 September 2026 the Town of Jackson, Wyoming, announced a boil water advisory mandated by the US EPA for all town water customers and connected systems after E. coli was detected in a raw groundwater well during routine monthly sampling, and Teton County School District cancelled classes for a day. The advisory was lifted on 26 September after two consecutive days of clean repeat samples. According to the town's public works director, the well had not been used for about two weeks, and the initial positive may have been a false positive or bottle contamination.
Viridis comment: This incident highlights the importance of correct and hygienic sampling procedures. A false positive can cause serious disruption and a loss of confidence in the drinking water supply.
This roundup summarises publicly reported information; see the linked sources for full details.
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