Birmingham-based utilities firm Severn Trent has continued its boardroom reshuffle with the departure of finance director Mark Wilson.
It claims the move is nothing to do with an Ofwat probe after whistleblowing allegations.
Mr Wilson, who will stand down at the end of the year, has left the company by mutual consent.
Severn Trent said the change would enable group chief executive, Colin Matthews, to continue developing his new management team.
Mr Wilson has agreed to stay in post until after the interim results scheduled for December 6.
Chairman Sir John Egan said: "We are very grateful to Mark for all the work he has done first with Severn Trent Water, then the whole group and now for helping to ensure a smooth succession process.
"He has made a significant contribution to the group's success."
Mr Wilson said: "I have had a tremendous ten years at the heart of three regulatory reviews in Severn Trent Water, and I am proud to have made a contribution to the water company's significant progress over that period.
"I am also pleased to have smoothly managed the finance role during a period of significant management transition. It is now time for me to refresh my own objectives and career."
A spokesman for Severn Trent said Mr Wilson's departure was unrelated to the ongoing Ofwat investigation into allegations of overcharging.
The water regulator launched an inquiry into claims customers had been overcharged by Severn Trent after it gave Ofwat misleading regulatory information.
The Severn Trent spokesman said: "This change is nothing to do with the Ofwat inquiry, this would have happened irrespective of that.
"When Mark was appointed last September, the background was totally different. Now we have a new chairman and new chief executive and a new team."