Whitehall officials are briefing ministers that the parlous state of Thames Water presents a “critical risk” to the UK, singling out a water treatment site in northeast London as particularly alarming. The company’s plans for Coppermills, which serves up to 3 million London residents, were reviewed by Ofwat in late 2019. The regulator agreed £350 million should be invested in resilience measures including “pre-treatment for algae” and “removing the single-point of failure” at the site’s pumping station. It’s not clear what progress has been made. Thames Water will publish its annual results on Thursday, followed by a verdict from Ofwat on plans to increase customer’s bills up to 59 per cent in order to attract more investment to repair and replace its ailing infrastructure. Without additional funds, the company says it will go bankrupt by next June. In March investors scrapped a promised injection of £500 million, saying Ofwat had made the company “uninvestable”. Hours before, the company’s board had approved a £150 million dividend.