His visit to the stricken southwestern county of Somerset came hours after the embattled head of the Environment Agency was confronted by residents but rejected calls to quit.
Cameron had earlier dispatched Royal Marines in all-terrain vehicles to evacuate a village in Somerset where floodwaters were rising.
Southern England has suffered what is thought to be its wettest winter since 1766 owing to a series of Atlantic storms that are set to continue for several weeks yet.
"Everything that can be done will be done and I'll make sure that happens," Cameron said after he arrived in the flood zone.
He met local residents, farmers and emergency teams, his Downing Street office said.
Cameron admitted the government had been wrong to halt the dredging of rivers in the area -- a decision residents partly blamed for the floods -- and said that "there are lessons to learn".
Environment Agency boss Chris Smith, who came under fire after suggesting this week that Britain may have to choose between whether to protect towns or the countryside from floods, said he was "very proud" of the response of his agency.
"I have no intention of resigning because I'm very proud of the work the Environment Agency and its staff have been doing," he said during his visit to the area.
Environment minister Owen Paterson was heckled by locals when he visited last week wearing smart black shoes instead of waterproof wellington boots.


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