Four fire engine and 21 firefighters and officers were called to a burst water main in Leigham Vale, Tulse Hill this morning.
Four residential properties, two commercial units and six residential garages were flooded to a depth of around 12 inches.
Crews isolated electrical supplies before the duty of care was handed over to Thames Water and the local authority.
The Brigade was called at 0746 and the incident was over for crews at 1216. Fire crews from West Norwood and Norbury fire stations attended the scene.