Four fire engines and around 25 firefighters were called to a burst water main in Wickham Lane in Plumstead.
Four cars were flooded to a depth of 25cm on nearby Woodbrook Road and two properties were also affected by water. Crews used a water ejector pump to remove the water.
The Brigade was called at 1047 and the incident was over for firefighters by 1409. Fire crews from Plumstead, East Greenwich and Bexley fire stations were at the scene.