Cameron was visiting the village of Yalding in Kent, southeast England, which has been badly flooded, when the unnamed woman told him in a heated on-camera exchange that she had been left stranded in her home without electricity.
She said: "We still have no electric. We need electric. As I say, the council, from Monday, we have been trying to contact them, but they have all decided to go on their holidays. Nothing."
Days of heavy rain have caused many rivers in southern England to burst their banks.
After visiting another house in the village that was also damaged by flooding, Cameron said: "Look at this man's house, I was just talking to. That was a flood barrier he got after 2000 -- quite a high flood barrier.
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The floods were "tragic events", he said, but he pledged that the authorities "have got to do more and we have got to do better".
Around 13,000 homes were still without power across Britain, the Energy Networks Association said.
Engineers have been working to restore power after 50,000 homes were left without electricity on Christmas Day. Power lines were brought down by storms.
Low-lying parts of the London commuter belt towns of Dorking, Leatherhead, Guildford, Godalming and Tonbridge have been particularly badly flooded.