UK water companies collected more than £340m in revenue last year by accepting 608 billion litres of industrial and commercial wastewater into sewage treatment works that experts say cannot remove most of the chemicals in it. The waste arrives from power stations, pharmaceutical plants, food factories, hospitals, abattoirs, and waste facilities — carrying substances including cyanide, chromium, cadmium, mercury, PFAS, flame retardants, solvents, and pharmaceuticals. What the biological treatment process cannot strip out flows into rivers, lakes, and seas as "treated effluent," or gets captured in sewage sludge and spread on farmland as fertiliser. The system operates with no independent regulator and no central register. Water companies issue their own "trade-effluent consents," police compliance with those consents themselves, and pocket the revenue. Environmental regulators have no direct role. Until now, no national picture of the system existed. Watershed Investigations, the Guardian, and River Action compiled a database of 26,000 consents to produce the first comprehensive map of the trade. The financial incentives run in exactly the wrong direction. An industry expert told the investigation that water companies have "a financial incentive to accept far more toxic material than they should." United Utilities led with £61.6m in revenue from industrial waste, followed by Yorkshire Water at £48.8m. Revenues have risen sharply — Anglian Water's increased 62% over five years. Thames Water accepted the largest volume at 113 billion litres, followed by United Utilities at 105 billion litres and Severn Trent at 79 billion litres. Checks on incoming waste are rudimentary. Water companies may take a sample and run basic pH tests, but these do not identify most contaminants. An Environment Agency officer said that by the time a problematic substance is identified, "it's already gone" into the treatment works. Landfill leachate — described by the EA officer as the agency's "greatest concern" because of the harmful chemical cocktails it can contain — arrives by tanker at sites like Davyhulme in Manchester and Avonmouth near Bristol, where lines of tankers queue outside the gates. The regulatory framework dates back more than 30 years, predating current understanding of substances like PFAS. The EA acknowledged the framework was "developed over 30 years ago" and said it was working to improve contaminant management. Water UK, the trade body, deflected to government, calling for bans on toxic substances and for manufacturers to pay removal costs. The Department for Environment, Food and Rural Affairs said water companies "should never profit from pollution" and pointed to its forthcoming clean water bill. The structural problem is that sewage works are biological treatment systems accepting chemical waste, with the entity profiting from the arrangement also responsible for policing it. The waste that survives treatment contributes to the overloading of sewer networks that triggers raw sewage spills — the same crisis that has generated public outrage and calls for nationalisation. The polluter-pays principle is inverted: industrial producers pay water companies a fee, water companies keep the revenue, and the public absorbs the environmental and health costs through contaminated waterways and farmland. River Action's head of campaigns, Amy Fairman, called for polluters to be "held to account and made to pay, rather than passing the costs and consequences down the line." The clean water bill is the government's stated vehicle for reform, but until an independent regulator oversees trade-effluent consents, the companies writing the permits and collecting the cheques remain the same entities with the least incentive to say no.
