A £250m desalination plant launched 12 years ago to increase drinking supplies during long dry spells has been put on hold, as water companies in England and Wales face growing political pressure over their management of the supply crisis. The Thames Water plant at Beckton, east London, opened in 2010 with plans to supply up to 1 million people during emergencies, but that ambition has been scaled back amid doubts as to when the facility can begin operating. Despite July’s heatwave and the driest eight-month spell since 1976, the Beckton plant will not start supplying drinking water until next year at the earliest, according to the Daily Telegraph. The company told the paper it had downgraded the estimated supply from the plant by a third. A spokesperson said: “This adjustment was made on the basis of experience and to avoid creating unrealistic expectations about the output that could be achieved over a sustained period.” He added that “planned work” had to be completed before the plant could begin operating. It means that even if a drought is declared in the Thames region, the plant will not operate. Experts said Thames Water had failed to take into account the varying salt water levels in the Thames estuary. Of the 11 water companies, two – Southern Water and South East Water – so far have decreed hosepipe bans even after pressure from the government to do more to curb excessive water use. The two Tory leadership candidates have called for tougher measures against suppliers that fail to tackle leaks. The former chancellor Rishi Sunak told the Telegraph he was considering offering compensation to customers if hosepipe bans were introduced as a consequence of water company failures. He said: “It is unacceptable for water companies to impose restrictions on their customers when they fail to stem leaks. We need tougher financial penalties on the companies that are not investing enough to stop water being wasted.” His rival, Liz Truss, is planning tougher regulation. A spokesperson for her campaign told the Telegraph: “We shouldn’t be in a position where hosepipe bans have to happen. More needs to be done to make sure water companies fix leaks and waste across their networks. “As prime minister, Liz would look at how best Ofwat could hold those water companies with the worst track record to account, so that hardworking people across the country are not restricted on their water use over the summer months.” South East Water said on Wednesday it had “no choice” but to restrict water use for 3m households from 12 August, saying demand this summer had broken “all previous records” during extremely dry conditions. But other companies, even in drier areas, are resisting imposing a ban. Those involved in drought discussions say companies would rather wait until the last minute, when rivers are running dry, rather than irritate customers by putting bans in place early. Yorkshire Water, which has reservoirs that are only 52% full, is among the companies holding firm against a hosepipe ban. Instead it is urging customers not to wash to their cars, and if they have to wash them to do so over lawns.