Police said Mard Kawisead, 51, was driving the pickup truck down a hill when he said the brakes failed.
All the injured – Thai, Mon and Burmese – were taken to Patong Hospital, and one man, named Chat, died in hospital. Three people suffered broken limbs.
Mard told police he was driving the workers back to their accommodation when he drove down a hill, and reached a curve. He tried to brake – unsuccessfully – and lost control, and drove the pickup into the concrete drain.
Mard has been taken to the police station for questioning.