More than 750,000 tonnes of toxic liquid from landfills are being mixed with sewage and spread on farmland across England each year, an investigation has found. Leachate, the liquid that drains through landfill waste carrying a cocktail of chemicals, is regularly tankered to sewage treatment works, where it mixes with domestic sewage and industrial effluent to create sludge, also known as biosolids.
The process produces treated liquid, discharged into rivers and seas, and solid sludge, sold by water companies to farmers as fertiliser. However, many toxic chemicals escape treatment, ending up in waterways or accumulating on fields. Currently, all of England's rivers fail to meet legal standards for chemical pollution.
Analysis by the Guardian and Watershed Investigations shows about 3.5 million tonnes of leachate are generated each year, with more than 750,000 tonnes sent to sewage works unable to deal with chemicals found in leachate such as PFAS 'forever chemicals', PCBs, dioxins, flame retardants, solvents, endocrine disruptors, and microplastics. An Environment Agency source described the practice as 'a form of laundering', adding that 'you lose the leachate in bulkier material to dilute and disperse it'.
Forensic scientist Dr Dave Megson said he was 'amazed that this was happening' and that 'it seems like the whole system is out of control'. He noted that most sewage plants were designed for human waste, not chemical effluents, and that adding large volumes of leachate could disrupt treatment efficiency. The Environment Agency source said 'the level of treatment just isn't there at most works' and that 'PFAS and similar chemicals just pass straight through'.
Leachate and sludge are locked in a cycle: it is sent to sewage plants as the cheapest disposal option, with water companies paid to take it and profiting by selling the resulting sludge to farmers. Farmers accept it as cheap fertiliser, while the water sector relies on them due to few alternatives. An Environment Agency source warned that cutting off leachate to sewage works overnight would trigger an 'absolute crisis', overwhelming specialist treatment facilities and forcing government intervention.
