Among the rumoured bidders were PowerGen and National Power, both of which have been barred from acquiring regional electricity companies, Eastern Group, now part of Hanson, and French and US utilities.
Anglian Water saw its shares rise 27p to 599p while Severn Trent was up 34p at 595p, Thames rose 35p at 599p and Wessex Water rose 28p to 360p.
Alan Smith, chief executive of Anglian, one of the favoured takeover targets, sought to dampen bid speculation, saying: "We have had no approaches ourselves and, while we constantly monitor the water and other utilities we have not seen any deal which would benefit our shareholders. We would move if we saw something that was right but we haven't yet."
Anglian and Eastern had examined a merger, he added, but decided that it was not worth paying the bid premium required.
Mr Smith was speaking as Anglian unveiled a 4 per cent rise in pre-tax profits last year to pounds 238.6m and a 15 per cent increase in the dividend for the year to 30p.
Despite being the driest area of the UK with rain levels in some places on a par with Israel and Morocco, Anglian survived last summer's drought without even a hosepipe ban.Reuse content