Sarah Bentley stepped down with immediate effect amid mounting worries over the company's debt which totals nearly 14 billion -- as the creaking sector faces a huge bill to clean up sewage.Canadian pension fund Ontario Municipal is its biggest shareholder with almost one-third of the group.
"The sector as a whole is financially resilient. Ofwat continues to monitor the financial position of all the key water and wastewater companies," it added. England's privatised water companies last month pledged to make massive investments to stop raw sewage being pumped into waterways as concerns mount about water quality and laxer environmental protections post-Brexit.