The accident happened on Aug. 24 when a 10-year-old girl in a swimming pool in Bangor, North Wales, sank to the bottom of the deep end.
A Poseidon monitoring system installed in the pool registered that a swimmer was in distress because she was at the bottom of the pool and not moving, and within three seconds sounded the alarm to the lifeguard on duty who pulled the girl out of the water.
The girl was resuscitated and taken to a hospital, where she recovered. Less than 40 seconds elapsed from the system alert of the potential drowning to the victim being pulled from the pool.
The Gwynedd Council installed the system at the pool for $118,000 (65,000 pounds) two years ago. Built in the 1960s, the 110-foot-long pool ranges in depth from 3.5 feet to 12.5 feet, making it one of the deepest in Wales.
The system alerts lifeguards that something suspicious is happening in real time and notifies them of the exact location of the incident. It is made up of a network of cameras mounted both above and below water level to monitor swimmers' trajectories.
Francois Marmion, general manager of Vision IQ, the company that developed Poseidon, said in a statement: "It is virtually impossible for lifeguards to see everything that is happening in the pool all of the time, given the warm, noisy and crowded environment in which they typically work."
The Poseidon system has been in other countries as well.
Steve Ranger of Silicon.com reported from London.