Bridgewater will join the company this summer from Sembcorp Industries where he is chief finance officer for the UK, South Africa and the Americas.
He will join the boards of Welsh Water and Glas Cymru as one of three executive directors. The board is chaired by Bob Ayling and also consists of seven independent non-executive directors.
Bridgewater currently has commercial and financial responsibility for eight businesses in the water and energy sectors including Bournemouth Water.
Chris Jones, Welsh Water’s chief executive, said: “The sector is facing many challenges including growing pressures on costs as well as significant regulatory reform.
“As a “not-for-profit” company, we will need to adapt so that our model continues to deliver significant benefits for our customers. Peter will help build on the sound foundations that have been laid since 2001 and is a strong addition to our board.”