A campaign group has lost a High Court challenge against the Government over proposed changes to rules around how sludge is used on farmland.

Fighting Dirty told a hearing in July that human health was being exposed to “unacceptable risks” due to the Environment Agency (EA) unlawfully removing a target date to implement its “sludge strategy”, which would change regulations on how the material was used on agricultural land.

The group claimed that sludge “is a by-product of treating wastewater in water or sewage treatment plans”, which can contain microplastics filtered out of sewage water to prevent polluting substances from reaching waterways.

The EA, as well as the Department for Environment, Food and Rural Affairs (Defra), which was an interested party, opposed the claim, telling the court that removing the date by which the strategy would be applied did not amount to a “legal error”.

In a ruling on Wednesday, Mr Justice Fordham dismissed Fighting Dirty’s claim, stating that the original 2023 target date was “unachievable” and that the Government had not acted “unreasonably” by removing it without giving a new timescale.

The court in London was told last month that around 96% of sludge produced in the UK, around 3.5 million tonnes, was spread as fertiliser across agricultural land every year.

But a 2017 report commissioned by the EA said that sludge contained dangerous contaminants, including dioxins and hydrocarbons which could harm crops and human health.

Barrister David Wolfe, representing Fighting Dirty, said that following the report, the EA announced its intention to change rules around how sludge was treated as it accepted that existing regulations were “outdated and inadequate”.

But he claimed that by removing and failing to replace the original target date to implement the strategy, the EA and Defra had “shifted from a position of agreed urgency to agreed inaction” over the issue and was “failing to address the acknowledged environmental harms”.

Mark Westmoreland Smith KC, for the agency, said in written arguments that while progress on adopting the plan had been delayed by issues such as the Covid pandemic, the plan remained the same.

He said the target date was “not a commitment but an aspiration” and that it was “plainly rational” not to replace it due to competing priorities for resources.

Ned Westaway, for Defra, said in his written submissions that the strategy merely set out an “ambition” for the timing of the plan which was “necessarily subject to circumstances”.

In his judgment, Mr Justice Fordham agreed that the EA was committed to updating sludge regulations but that the target date to enact the strategy was “necessarily aspirational” as the EA relied on the government to change the law.

He said: “The Agency has had an unstinting ongoing resolve, that the regulatory change is the right thing for environmental protection, and that it would wish to see the change implemented.”

He continued: “I cannot accept that the action of not including a target date in the reissued August 2023 Sludge Strategy was (an) action outside the range of reasonable responses open to the decision-maker.

“Nor can I see any unexplained evidential gap or leap in reasoning which fails to justify the conclusion that it was not appropriate to include a replacement target date.”

Fighting Dirty was also ordered to pay £10,000 of the EA’s legal costs.

Following the ruling, Georgia Elliott-Smith, of Fighting Dirty, said: “Today’s findings show how the EA was placed in an untenable position, fully prepared to advance necessary regulations, yet hamstrung by political delays. This has allowed water companies to continue polluting with impunity.

“The solution is clear and has been long determined: bringing sewage sludge into the existing environmental permitting regime. While we understand the judgment, it highlights the total failure to regulate an extremely dangerous environmental hazard.”

An EA spokesperson said: “We welcome the judgment handed down this morning.

“We remain committed to the safe and sustainable use of sludge in agriculture and will ensure water companies can contribute to productive farming whilst meeting their environmental obligations to clean up waterways and promote soil health.

“We continue to work closely with Defra to improve the regulatory framework for the use of sludge.”

A Defra spokesperson said: “We are clear that we need to see the safe and sustainable use of sludge in agriculture to help clean up our waterways and promote healthy soil.

“We are working closely with the Environment Agency to undertake further assessment of the current legal framework.”