Water companies in England have faced a barrage of criticism as data revealed raw sewage was discharged for more than 3.6m hours into rivers and seas last year in a 105% increase on the previous 12 months. The scale of the discharges of untreated waste made 2023 the worst year for storm water pollution. Early data seen by the Guardian put the scale of discharges at more than 4m hours, but officials said the figures were an early estimate. The Liberal Democrat leader, Ed Davey, said the scandal of raw sewage pouring into waterways should be declared a national environmental emergency. He called on the government to convene an urgent meeting of the Scientific Advisory Group for Emergencies (Sage) to look at the impact of sewage pollution on people’s health. Total discharges from the 14,000 storm overflows owned by English water companies that release untreated sewage into rivers and coastal waters increased by 54% to 464,056, according to data submitted to the Environment Agency by the industry. Senior industry figures highlighted the heavy rainfall over the autumn and winter that put huge pressure on the sewerage system. But storm overflows are supposed to cope with heavy rainfall and only be used in exceptional circumstances, like major storm events. Climate change has long been predicted to bring higher rainfall levels. One senior executive told the Guardian: “We have wasted 15 years, we have not been investing enough.” The data on discharges from storm overflows reveals the duration and the number of discharges from individual overflows across the network in England. The 3.6m-plus hours of raw sewage and rainwater discharged over the year includes huge spikes in some outflows. Forty per cent of South West Water outflows discharged raw sewage more than 40 times, while nearly a third of United Utilities outflows and 23% owned by Yorkshire Water discharged 60 times or more. Any outflow that has more than 60 discharges a year should prompt an Environment Agency investigation. As well as total discharges soaring from just over 301,000 in 2022, the average discharge per storm overflow has increased to 33, an increase of more than 43.7%. Some companies had much higher average spills per outflow, with South West Water averaging 43 per outflow and United Utilities 45. Some of the highest rises in the hours of raw sewage pouring into rivers were by Anglian Water, with a 205% increase to 273,163 hours, Wessex Water a 186% increase to 372,341 hours, Thames Water a 163% increase to 196,414 hours, and Northumbrian Water a 160% increase to 280,029 hours. Severn Trent discharged raw sewage into waterways for 440,446 hours, South West Water for 530,737 hours, an 82.5% increase, Southern Water for 317,285, a 116% rise, and United Utilities for 656,014 hours, a 54% increase. Thames Water was responsible for the biggest increase in the number of discharges, with its overflows dumping on 16,990 occasions, a 112% increase on 2022. A Guardian analysis of the data revealed the River Irwell and its tributary, the Croal, which flows through to Salford and Manchester, had the highest levels of sewage spills. Nearby storm overflows spilled just under 12,000 times in 2023, or 95 spills per mile of water, the highest rate of all rivers in England. Second worst in England was the River Darwen, near Blackburn and Preston, where there were more than 3,000 sewage spills from nearby overflows in 2023 – equivalent to 83 spills per mile. Just one river in the south of England features in the worst 10: the River Avon, as it makes its way through Bath and Bristol. This urban section of the river had 6,573 sewage spills in 2023, or 74 spills per mile, making it the third most polluted in England. Also top of the list for sewage spills was the River Calder near Huddersfield, the Aire near Bradford and the lower section of the Tyne around Newcastle and Sunderland, the Guardian’s analysis of Environment Agency data found. Criticism was not reserved for the industry. The government’s much vaunted plan to tackle raw sewage pollution gives water companies a deadline of 2035 to reduce the amount of sewage flowing into bathing water and areas of ecological importance, but discharges would continue being released into other waterways until 2050, at a time when the climate crisis is increasing rainfall intensity and frequency, putting more strain on the sewerage system. Davey said the scandal had to be treated as an environmental national emergency. He said: “Only by treating the sewage scandal with the urgency it demands can we save our rivers and beaches for future generations to enjoy. Rishi Sunak and the Conservative party have failed to listen and as a result sewage spills are increasing, our precious countryside is being destroyed and swimmers are falling sick.” The record sewage discharges were revealed as a major investigation into illegal sewage dumping by the regulator Ofwat into more than 2,000 treatment plants was nearing its conclusion. The Environment Agency is running a parallel criminal inquiry into illegal sewage dumping by companies. Storm overflows are supposed to be used only in extreme weather but for many years they have been used routinely, discharging raw sewage even on dry days in some cases. The academic Peter Hammond has shown how water companies are routinely using storm overflow discharges in their water management. Campaigners turned their ire on the industry as the scale of the discharges was published. Ash Smith, who has investigated sewage pollution in the River Windrush for several years, said: “Water companies will blame the weather but it’s very clear from the data analysis done by Prof Peter Hammond that many sewage-dumping – we refuse to call this spilling – events are illegal either because sewage works simply don’t treat the amount they are required to or they do it in dry conditions. “This is the information that needs to be made public along with volume, not just hours.” Only two water companies, Southern and Thames Water, publish real-time data on raw sewage releases from outflows. Smith said greater transparency was needed. “How the other companies have been allowed to get away with keeping easily provided data public is a mystery. It is compounded by the secretary of state’s silence on getting them to reveal what will undoubtedly be a scandalous state of affairs.” The shadow environment secretary, Steve Reed, said the government should immediately impose his plan for a ban on bonuses for water company executives. “Despite being responsible for this illegal behaviour, water company bosses have brazenly awarded themselves over £25m in bonuses and incentives since the last election,” said Reed. Labour has not committed to any restructuring of the privatised water industry, even as Thames Water, which is struggling with debts of more than £14bn, is facing being taken into special administration. The Liberal Democrats are calling for Thames, the biggest of the privatised companies, to be put into special administration and turned into a public benefit company. The Environment Agency director of water, Helen Wakeham, appeared to play down the scale of the increased pollution, saying it was not surprising that the discharges had increased. “We are pleased to see record investment from the water sector, but we know it will take time for this to be reflected in spill data – it is a complex issue that won’t be solved overnight.” The water minister, Robbie Moore, said: “Today’s data shows water companies must go further and faster to tackle storm overflows and clean up our precious waterways. We will be ensuring the Environment Agency closely scrutinise these findings and take enforcement action where necessary.” The revelation of the scale of releases into waterways comes as rivers in England are at crisis point, suffering from a toxic cocktail of raw and treated sewage pollution, chemical toxins and agricultural runoff. In the last few weeks, ministers have engaged in a flurry of announcements in anticipation of the shocking data on record sewage spills. These included an announcement of a £180m plan to fast-track action on sewage discharges, in the face of criticism not enough is being done. The industry is planning a record £96bn to the end of the decade to tackle sewage discharges, leaks and the impending water supply crisis but has been criticised for passing on the costs to customers for investment that should have been carried out years ago. Water UK, which represents the industry, said: “These results are unacceptable and demonstrate exactly why we urgently need regulatory approval to upgrade our system so it can better cope with the weather. We have a plan to sort this out by tripling investment which will cut spills by 40% by 2030 – more than double the government’s target.” Ofwat has to decide whether to allow companies to increase water bills to pay for the investment. Water UK said the investment was vital and Ofwat must give the industry the green light to get on with it.