The jobs cuts will save £7m
The UK's biggest water company is to axe 300 jobs due to the recession.
Thames Water said most of the cuts will be in support services in Reading and Swindon, and that customers would see no reduction in services.
The firm said the recession was reducing its revenue, partly as more customers were unable to pay bills.
Compulsory redundancies have not been ruled out by Thames Water, which supplies 13.6m customers in the London and the Thames Valley area.
The job cuts will save the company, which employs 5,000 staff, about £7m.
Chief executive David Owens said: "We have been planning a remodelling of the business, to be rolled out this year, which will allow us to meet future challenges.
"A number of redundancies had always been planned as part of this restructuring process.
"However, the recession, which is reducing our revenue, and driving up borrowing costs, has meant that we have had to bring this programme forward.
"This should allow us to reduce running costs while maintaining our services to customers."
Gary Smith, national officer of the GMB union, said: "We want to meet Thames Water to discuss these job cuts.
"We will take some convincing that there is an economic case for these job losses."