Flood defences will not be completed nationwide within five years, the Environment Agency (EA) has admitted.
And in some flood hotspots, such as York and Lewes, flood barriers may take up to ten years, if allocated at all.
An EA spokesman said: "It's a lengthy and ongoing process. Although the £564m will take us up to 2006, we then need further funding to maintain and build flood defences.
"We have to access each area individually, build a hydraulic model, gain planning permission to build the defences and so on. Not all the work can be done within five years."
This leaves insurers uncertain of flood black spots and left to pay out claims for the next five years under the commitment agreed across the industry in January.
Norwich Union (NU) and Direct Line want the EA to identify which areas qualify for flood defences, and the true cost of flooding.
Edward Yorke, proprietor of Lewes-based Berkley Alexander Brokers, said: "The whole process is too slow and nobody is addressing what we are going to do in the meantime. If flood defences do not happen within five years, homes will be blighted."
Environment minister Elliot Morley proposed last week to tax developers who build on flood plains, ruling out a flood tax on people who lived in flood-prone areas. Local flood defence committees will be wound up and a single-tier of regional communities will be created.
