The utility company has launched an independent review into why areas of the capital have experienced serious flooding and how it can prevented in the future.
Furious Kensington and Chelsea residents and politicians questioned leaders at Thames Water after dozens of people were forced out of their homes following several severe rain storms, which caused millions of pounds worth of damage.
Water and sewage poured through the streets and seeped into homes, shops and restaurants in Notting Hill’s world-famous Portobello Market during two particularly bad downpours in July. There was further flooding earlier this month.
At a meeting on Monday night Thames Water’s director of corporate affairs George Mayhew apologised for the company’s “unacceptable” response to people whose homes were ruined and agreed that it had been implementing “band aids” for years instead of finding a permanent solution to the problems.
Areas of east London also severely flooded in July and the company’s phonelines were blocked with calls from victims unable to get help.
Mr Mayhew claimed sewers saw a month of rain in just an hour during one storm on July 12.
“I absolutely admit that our response on the days and the evenings of the floods was not what it should be at all,” he said.
“People couldn’t get through and if they did they were on the phone for hours. It was unacceptable. In terms of the broader piece around the [Thames Water] assets, the assets were designed to cope with a certain amount of weather.
“The whole point of having the review is that these weather events are going to become more frequent if you believe, like we do, in climate change.
“We need a set of solutions that will be the right ones for the years ahead. When we do this we want to get it right.”
He added the leadership team “had not been up to scratch”.
“Thames Water for too many years has not been providing the service that our customers deserve,” he said.
“One of the things the new leadership team have done is we have lifted the covers to see the extent of the challenges Thames Water has. They are significant.”
Some residents told the meeting that they had not been able to return to their flats since the floods hit and it would take a year for repairs to be finished.
Others described elderly neighbours being trapped in their homes “up to the chests” in water, which came in through drains, walls and toilets.
The review is expected to take at least six months to complete and be ready next spring.
Regulator Ofwat said it will be monitoring the recommendations that come from the report and it will require Thames Water to take action in the short term to deal with any future heavy rainfall.
Residents who had Flooding Local Improvement Projects (FLIPs) , which stop the sewers surcharging into basement properties, installed in their homes had less damage.
But Thames Water said it cannot install more FLIPs because they might just divert water to another area, causing further problems. Installing larger or new sewers can take more than a decade, the meeting heard.
Mr Mayhew said the review would seek to highlight ways the capital can prepare for more extreme weather.
He added: “This event in July was of such magnitude, certainly I would say in Thames Water’s history.
“I feel it is a moment in time where this data, the results of the review, is a moment where we really can sort of make sure that we know that these extreme storms are going to happen more and more frequently and we know we need a Thames Water council and highways network that can handle more extreme weather.”
The meeting comes just a few weeks before the COP26 world climate summit when extreme weather such as flooding will be among topics discussed.