Mr Cleary was formally appointed on Friday after serving as acting chief executive officer for several months after the departure of predecessor Jim Bentley.

Mr Bentley was named the NSW government's chief executive officer for the NSW water sector last year.

"I am confident Darren will continue to provide strong leadership at Hunter Water, building on his extensive experience at the agency, including most recently as acting chief executive officer since February," Mrs Pavey said.

"Darren brings more than 25 years' experience working for utilities in the water sector and his appointment will allow Hunter Water to continue to deliver on its outstanding customer experience, while advancing key policy and strategy areas."

Mr Cleary has an impressive CV and has a Bachelor of Engineering, Environmental, Honours from the University of NSW and a Master of Engineering Management from the University of Technology Sydney.

The appointment followed an international search, Hunter Water chairman Terry Lawler said. "This is a challenging time for everyone in our organisation and community," Mr Lawler said.

Water storage in the Hunter was down 1.6 per cent on last year at 67.5 per cent according to data on Friday.