Residents across a large part of SE1 from The Cut to Shad Thames woke up on Sunday morning to find their water supply cut off due to a major burst water main in Tooley Street.
The burst water main was at the junction of Tooley Street and Shand Street, between the Unicorn Theatre and the Magdalen restaurant. The fire brigade was called to the scene just after 9.30am on Sunday.
Water was also flowing into nearby basements as well as into the building site for PricewaterhouseCoopers' new building on the More London estate.
Thames Water says that a 20" main has burst which has led to households in many SE and SW postal areas losing water supply or experiencing reduced pressure.
The water company says that it has as many staff as possible at the scene working to relieve the flooding and isolate the main, assisted by the London Fire Brigade.
The fire service brought in a high volume pump to drain water from a number of commercial premises. 20 firefighters and four fire engines were at the scene on Sunday lunchtime.
A Thames Water spokesman has told the London SE1 website that the firm hopes to restore normal water pressure by 4pm on Sunday.