Fraser, who has been at the FTSE 100 group for 14 years, will leave in the autumn, though the exact date is not yet confirmed.
UU chief executive Steve Mogford, who has been in place since 2011, hailed Fraser’s “significant contribution” to the operational progress the group has made and for developing a “strong and talented leadership team beneath him”.
He noted that the departure comes at a time when the industry is finishing the current five-year regulatory period with UU in a “strong position” for the next.
Water industry regulator Ofwat recently delivered its initial fast-track assessment of the company’s business plan for the next regulatory period, covering 2020 to 2025, setting out the prices the companies can charge over the coming years. Analysts said the regulator’s calculations included “slightly more conservative” estimates for both allowed returns and outperformance.
UU last month reported full-year underlying profits up 24% and pledged to increase investment by another £100mln.
The sector has also been under pressure in recent months due rising political concerns, as the Labour party has outlined its plans to re-nationalise the industry, with reports indicating a Jeremy Corbyn-led government would not expect to pay any premium to shareholders.
At Cadent, chief financial officer Steve Hurrell, who stepped up to become interim CEO in February this year after Chris Train confirmed his plans to retire, will remain CEO until the autumn and then return to his role as CFO.
The gas distribution network, another industry that Labour wants to nationalise, last month said it was likely to cut up to 400 jobs, about 10% of its workforce, it it overhauls the business.
UU shares were up 0.5% to 828p on Friday afternoon.