Liz Truss, the environment secretary, conceded that flood defenses had been “overwhelmed,” and Mr. Cameron promised to review spending plans, attempting to pre-empt criticism of the country’s state of preparedness. “You should look at what you’ve spent, look at what you’ve built, look at what you’re planning to spend, look at what you’re planning to build, and ask whether it’s in the right places, whether it’s enough, whether we’re doing everything we can to try and help,” Mr. Cameron said.

Although flood barriers had made a difference, he added, “It’s clear in some cases they’ve been overtopped, they’ve been overrun, and so of course we should look again at whether there’s more we should do.”

With the government seeking to restore its finances to health since the global economic crisis, spending has been constrained, and critics argue that investment in flood defenses has suffered. Kerry McCarthy, the spokeswoman on environmental issues for the opposition Labour Party, praised the emergency services on Sunday and the “strength of spirit” within the communities affected, but she added that “so-called unprecedented weather events are here to stay.”

“The government must drop its complacency over the need for climate change adaptation,” Ms. McCarthy said. “It must also invest in maintaining flood defenses, rather than cutting them as they had planned, as well as look urgently at what else can be done to reduce flood risk in future.”

John McDonnell, Labour’s economic policy spokesman, said that “as politicians we must not just sit idly by watching these awful scenes on TV, but come together to act.” He called for a “cross-party approach to securing a long-term stable plan for investment in a program that enables us to adapt to climate change.”