Holliday joined the board of directors of Northumbrian Water in 1991. He was elected its chairman in 1993. During his leadership, he expanded company's coverage until it provided water for the North East of England. It was also a period of upheaval with the company being bought by Lyonnaise des Eaux, a French company which later merged with another to become Suez; Northumbrian Water was sold in 2003, becoming once more British owned. He stepped down as chairman in 2006.
