The discharge of about 16 million litres of raw sewage into a northern Sydney suburb has resulted in a fine of more than $365,000.

After a sewerage system owned and run by Sydney Water partially collapsed, sewage containing urine and faeces backed up and overflowed at Naremburn in late October 2020.

Facilities including a park, playground and walking track were impacted by the spill.

The state-owned body pleaded guilty to three offences of polluting waters contrary to environmental law and was sentenced on Wednesday in the NSW Land and Environment Court.

Judge Sarah Pritchard found that between October 26 and 30, 2020, about 16 million litres was discharged and entered Flat Rock Creek.

“That is, on any view, a considerable volume of sewage,” she wrote.

In response to the incident, Sydney Water engaged in site remediation, provided temporary accommodation to affected residents, continued to monitor water quality, and improved the maintenance and reporting of its sewage system.

Sydney Water expressed genuine remorse over the incident with Iain Fairbairn, head of wastewater and environment, telling the court it had “fallen short” of what it was required to do.

“In particular, I express remorse and contrition on behalf of Sydney Water for the incident and for the resulting impact on the environment and our customers,” he wrote in an affidavit.

“Sydney Water recognises and accepts that the pollution is not acceptable.”

Judge Pritchard fined Sydney Water $562,500 but discounted this by 25 per cent due to the organisation’s early guilty pleas.

The maximum penalty it could have faced was $3 million.

The judge found Sydney Water’s conduct was “inadvertent and not deliberate” and that it was not negligent or reckless.

The collapsed section of sewer had been constructed between 1916 and 1930.

Despite this, Sydney Water could still have taken active steps to investigate and repair its ageing infrastructure, the judge said.

The state-owned corporation has been convicted nine times for prior environmental offences, including five incidents in which millions of litres of sewage polluted other waterways.

While Judge Pritchard could not say that Sydney Water would not reoffend in the future, she found the steps taken to improve its sewerage network reduced that possibility.

A spokesperson from Sydney Water said it would work with the state’s Environmental Protection Agency to make further improvements to its network.

“Sydney Water’s top priorities are the safety of the community and the protection of the environment.”