John Cuthbert, managing director of Northumbrian Water Group, is pulling the plug on his career in the water industry next year.Cuthbert will remain in place for the duration of the impending 2009 Periodic Review by the water regulator Ofwat and retire at the end of the company's financial year on 31 March 2010, when he will step down from the boards of Northumbrian Water Group and Northumbrian Water Limited.Cuthbert took over as managing director of the former Northumbrian Water Group plc in 2001 and continued as managing director of the company in 2003 when it was refloated on the London Stock Exchange.