The Government must not just react to flooding events as they occur, MPs have urged in the wake of the winter floods which racked up a £1.3 billion bill.
The parliamentary Environmental Audit Committee (EAC) warned of a lack of long-term strategic planning to protect communities at risk, with government spending on flood defences fluctuating year by year.
The MPs issued their warning in a report which follows the storms in December 2015 and January 2016 that caused floods in the north of England and Wales and parts of Scotland and Northern Ireland , with insured losses totalling £1.3 billion.
In the face of more frequent and intense flooding because of climate change, "it just isn't good enough" for the Government to react to events as they occur, the committee's chairwoman Mary Creagh said.
Government f unding for flood defences was initially cut in the last Parliament and only increased in reaction to floods in winter 2013/14, the report said.
The condition of flood defences had declined due to cuts in the amount of money to maintain them.
Important infrastructure was not currently protected to a consistent standard, while local councils were not getting enough support to develop plans to deal with flooding, it found.
The Government has committed to spend £2.3 billion on building new defences and to protect spending on maintaining existing defences.
But the MPs warned they were "sceptical" the Government would reach its target of protecting 300,000 properties, as it was based on an optimistic forecast that assumed the greatest efficiency in spending decisions.
And the committee said it was surprised to learn the extra £700 million funding for flood defences announced in this year's Budget was based on a "political calculation" and may not be allocated with the same strict economic criteria as the £2.3 billion.
This could lead to inefficiencies in flood investments, poor decision-making and outcomes that were potentially unfair to some regions, the report said.
Ms Creagh said: "We know that flooding is projected to get worse and and occur more frequently because of climate change, so it just isn't good enough for government to react to flooding events as they occur.
"Communities at risk deserve certainty from government."
And she said: "The Government needs to put money into the upkeep of existing flood defences as well as investing in new defences.
"Failure to do so can have terrible consequences for residents and businesses when defences fail.
"Any decline in the condition of critical flood defences represents an unacceptable risk to local communities in flood prone areas," she said, urging the Government to aim to have almost all critical defences meeting the "required" condition by 2019.
Peter Box, environment spokesman for the Local Government Association, said councils were at the sharp end of dealing with flooding, and were doing everything they could to protect communities and reduce risks to residents.
"However, we agree with the committee that councils need to be better supported by government.
"New measures that could make a positive difference include devolving new flood defence funding to local areas, further incentives for private sector investment in flood defences and mandatory flood-proof requirements for new homes and offices," he said.
An Environment Department (Defra) spokesman said: "Our six-year capital investment programme for flood defences will bring an end to year-on-year fluctuations in spending so communities can have certainty in future funding.
"Our National Flood Resilience Review will be published shortly, delivering immediate actions to better-protect communities ahead of this winter.
"This will be followed by our 25-year environment plan later this year setting out a new approach to managing our rivers across whole catchments, keeping homes, businesses and infrastructure safer from flooding."
The National Flood Forum welcomed the report and said it hoped the findings would influence the Government's resilience review "significantly".
The flood victim support charity's chief executive, Paul Cobbing, said "much, much more" was needed for communities to feel safe from flooding.
"As it stands, long-term flood risk management is inadequate to deal with the scale of the problem, both in approach and in the level of funding," he said.
"Communities want honesty about what the real levels of risk are and the implications for people, businesses and society."