Safety of Mullum’s water supply raised

The failure of the Mullumbimby Water Treatment Plant (WTP) to consistently provide the town with water of compliant quality represents a ‘risk to public health’ and immediate intervention is required, a report commissioned by Byron Shire Council has found.

The report, prepared by CWT Water Treatment Specialists, was presented to a meeting of Council’s Water and Sewer Advisory Committee last Thursday.

It examined daily log data from the ageing Mullum WTP over a three-and-a-half-year period from 1 January, 2022 to 24 July this year.

The report found that the water coming from the plant failed to consistently meet decontamination standards (known as ‘Log Removal Values’) as required by NSW Health and the Australian Drinking Water Guidelines.

The plant is also failing to consistently meet required turbidity levels as set out in the Council’s Drinking Water Management Strategy.

Turbidity: cloudiness or murkiness of water

Turbidity refers to the cloudiness or murkiness of water, caused by suspended particles, and is a key indicator of water quality and clarity.

‘Elevated turbidity compromises pathogen removal performance, particularly for protozoan species,’ the authors of the CWT report stated.

They said that this ‘further undermined confidence in the plant’s ability to deliver safe drinking water’.

‘The results indicate that immediate intervention is required.

‘Given the number and severity of exceedances, it is highly likely that operational adjustments alone will not resolve the issue.

‘Until such issues are addressed, the WTP cannot be considered compliant with current microbial safety standards and there remains a risk to public health during periods of poor filter performance.’

The Mullumbimby WTP currently supplies treated water to approximately 3,600 people in 1,620 residential properties, along with 270 non-residential properties.

Concerns about its capacity to consistently deliver high-quality water to Mullumbimby were a major factor behind Council’s decision in August last year to decommission the WTP and permanently connect to the Rous County Council (RCC) supply.

However, on 24 October 2024, the newly-elected Council deferred this decision, choosing instead to consider a range of other options to provide the town with a consistent, sustainable water supply.

This change of heart was driven by a desire for Mullumbimby to retain its own water supply – a sentiment supported by a significant proportion of Mullumbimby residents.

UV disinfection system not implemented

According to written Council staff comments accompanying the CWT report, after the deferral decision was made Council’s utilities department recommended that a UV disinfection system be purchased to improve the WTP’s performance.

However, staff were told that Council could not afford the $967,200 price tag for this upgrade.

This led to a ‘recommendation to defer the project and notify NSW Health,’ the staff comments state.

The authors of the CWT report and Council staff are now strongly recommending that Mullum’s supply be switched to the emergency Rous connection when planned works on the WTP are undertaken next month.

They say this connection should be retained until a long-term water supply solution has been implemented for the town.

An alternative water supply

‘Given the circumstances, an alternative water supply is required to ensure the ongoing supply of safe drinking water to Mullumbimby,’ staff said.

‘A prudent course of action is to extend the temporary shutdown of the Mullumbimby WTP beyond the weir upgrade period and continue supplying Mullumbimby via the RCC trunk main.’

Council has not communicated the concerns about Mullum’s water supply, as set out in the report, to residents or the broader community.

Only those, like The Echo, who choose to trawl through the agendas of Council committee meetings published on Council’s website, would be aware of the latest findings.