Trade unions, celebrities and river activists are calling on the new UK government to halt attempts by the water industry to raise customer bills in England and Wales by up to 91% and immediately start a root-and-branch review of water ownership. The author Michael Rosen and comedians Nish Kumar and Stephen Fry joined campaigners from Greenpeace, Surfers Against Sewage, River Action, the Rivers Trust and activists across the country in signing a letter to Keir Starmer urging him to step in, days before the regulator Ofwat is to announce whether it will approve huge increases in customer bills across England and Wales. Some of the most polluting and financially struggling water companies, including Thames Water and Southern Water, are seeking the biggest increases in bills. Thames Water wants customer bills to rise by 59% after accounting for inflation. Southern is seeking to raise bills by 91% by 2030, to £915 a year. The letter, organised by the campaign group We Own It, was also signed by the GMB and Unite unions. It says: “Saturday marked 35 years since the Water Act 1989 established our current model of water and sewage management, including privatisation and top-down regulation. “Bills have risen at twice the rate of inflation. No new drinking reservoirs have been delivered. A quarter of our supply leaks out of our pipes. Debts are unpaid; plans ‘uninvestable’. And last year, operators released sewage for over 3m hours into our rivers and seas. “If the current failed model remains in place, Labour could be fighting the next election with some bills topping £915 a year and sewage a greater threat to our health than ever.” The letter calls on the prime minister to pause the current price-setting process and start a root-and-branch public review of ownership and regulation immediately, including consultation with water campaigners, trade union representatives and customers. Water companies are promising their biggest ever investment of £100bn to fix ageing infrastructure, cut sewage discharges and build new reservoirs, 35 years after the sector was privatised. They are acting after a public outcry over sewage pollution in rivers and seas, and a decline in the state of English rivers to a situation in which no river is deemed to be in good health. As well as concern over river health, there are growing fears about the threat to public health from the way wastewater is treated in England. The chief medical officer for England, Prof Chris Whitty, has said public health must be central to future investment in a new wastewater system to protect people from waterborne diseases from contact with rivers and coastal waters polluted by treated and untreated sewage. The regulator Ofwat, which is itself under pressure for allowing companies to pay dividends of £78bn in the past three decades while building debts of £60bn, will on Thursday announce whether it approves the business plans of the main water and sewerage companies. The Ofwat decision, which was delayed until 11 July because of the general election, comes amid a growing crisis in the water sector. Thames Water, the biggest privatised water monopoly, is struggling to stay afloat with debts of almost £15bn, and investors are threatening to pull the plug on the company. Ofwat has flagged concerns over the financial resilience of other privatised companies, including Southern Water, SES Water and South East Water, as of the highest concern. The financial resilience of Yorkshire Water and Portsmouth Water is also of concern by the regulator. ​ “No other country in the world runs water and sewage in the way we do: 90% is publicly owned and delivered,” the letter to Starmer says. “Regulation has been flawed, captured, and underfunded: a constant threat of the current model. Accountability must be reviewed, including putting community representatives on company boards and using ‘sunshine regulation’ to deliver greater transparency.”