The role encompasses Thames Water's media relations and internal comms activity.
Tucker, who was Maitland's lead director on the Thames Water account, will work with director of external affairs and sustainability Richard Aylard and Ben Kay, head of digital, brand and marketing. He will report to CEO Steve Robertson.
Thames Water, which has 15 million customers across London and the Thames Valley, came under fire earlier this year when supplies were cut for several days in a number of regions. The disruption was caused by a post-snow thaw caused burst water mains and leaks.
Tucker previously held senior communications roles at Nomura International and worked for 16 years as a journalist at The Daily Telegraph and the Financial Times, in London, Sydney and Hong Kong.
Robertson said Tucker had "proven credentials, having spent 25 years working in the media and in communications, both in-house and as a consultant".
He continued: "This all-round experience will be a huge asset to Thames as we embark on a new chapter. Thames is committed to putting customers first in everything we do - and best-in-class media relations and internal communications are both vital pillars to achieving success."