It took staff at the Asda supermarket in Chesser five hours to fix the sprinkler, which was spraying water over the warehouse area yesterday. The store was closed from midday till after 5pm, a time when many families do their weekly shopping.
Jo Newbould, spokeswoman for Asda, said: "There was a faulty sprinkler head, which caused a small flood in the warehouse.
"There is only a small amount of damage and the shopfloor area was completely unaffected, so customers shouldn't notice anything."
Staff were assessing the level of damage last night and were unable to say how much stock had been affected.