Bristol Water is being bought by Spanish utility group Agbar for £170m.
Agbar is based in Barcelona
Barcelona-based Agbar said that Bristol's board had accepted the offer and was recommending that its shareholders follow suit.
Bristol Water supplies about one million customers in the city of Bristol and the counties of Somerset, Gloucestershire and Wiltshire.
Agbar is offering £10.60 per Bristol Water share, plus an additional special dividend of 22.5p per share.
Numerous Spanish suitors
Agbar's offer currently has the support of 32.2% of Bristol's shareholders.
The bid is the latest in a number of offers coming from Spanish companies seeking to takeover UK businesses.
Fellow Spanish firm Ferrovial is currently making a hostile bid for airports group BAA, and Telefonica recently bought mobile phone network O2.
Bristol Water was formerly known as Bristol Waterworks Company, which was formed on 16 July 1846.