A nine-year-old boy drowned in a septic tank, which was under construction at a building site near Mangadu on Monday evening. Police believe the boy slipped and fell into the pit while playing with his younger brother nearby. Mangadu police identified the deceased as Suraj, a native of Bihar who lived with his family in Periyapanichery. His parents found his body floating in the tank, which had been left open with over four feet of water in it. No arrest for negligence was made as of Tuesday night.