Michael McNicholas, the chief executive of Irish Water’s parent Ervia, is to step down from the role in May, the group said on Tuesday.

Ervia, which also owns Gas Networks Ireland, formerly Bord Gáis, said it will shortly begin the process of seeking a candidate to succeed Mr McNicholas.

Mr McNicholas was appointed chief executive of the group in May 2013. Prior to joining Ervia, he served as chief executive of NTR and also worked at the ESB for 28 years.

“The decision to leave Ervia has not been an easy one. While my time at the company has been very challenging, it has also been very rewarding,” he said.

Mr McNicholas’s tenure as head of the semi-state company, which rebranded after Bord Gáis Éireann 2014 sale to Centrica, was marred by controvery.

He was repeatedly forced to defend the establishment of Irish Water and also came under pressure for holding shares in NTR, which part-owned Celtic Anglian Water Ltd (CAW), a company that had contracts with Ervia’s subsidiary for meter installation and waste water.

Commenting on his decision to leave Ervia, chairman Tony Keohane said the company regreted losing someone of Mr McNicholas’s calibre.

“Michael has played a key role in the establishment of Ervia and has led the company through its complex and demanding evolution from its origins as Bord Gáis Éireann. That journey involved the sale of the Bord Gáis Energy business, the formation of Gas Networks Ireland and the creation of Irish Water,” said Mr Keohane.

“Under Michael’s leadership, Ervia has built a high quality team that has continued to develop the State’s gas network and made very significant progress towards the required transformation and rehabilitation of the Ireland’s water and wastewater infrastructure,” he added.