The Water Supplies Department director apologised yesterday after a burst main in Wong Nai Chung Road cut off supply to some of the city's busiest areas on Tuesday. Ma Lee-tak said 21 tanks were distributed on four water wagons during the day. He said the repair work had been extensive and involved turning off 20 valves on the main and feeder pipes to ensure the road was not flooded. He said emergency systems would be reviewed and the distribution of water tanks improved.