Firefighters received more than 100 calls to flooding incidents after torrential downpours hit parts of Newport, Monmouthshire and Torfaen.
A woman was rescued after drains outside her basement flat flooded
Dozens of properties were affected by flash flooding overnight on Tuesday, although there was no serious damage.
In Newport, one woman had to be rescued from her basement flat after becoming trapped inside by water.
South Wales Fire and Rescue Service said the rain was so heavy in parts of their area that drains could not cope.
Water was several inches deep in some places and the fire service received 113 calls in all to flooding incidents in Cwmbran, Abergavenny and Undy overnight.
Water building up on Newport Road, Caldicot, following downpours
Dozens of properties were affected by minor flooding as drains failed to cope with the volume of water but the level of which was too shallow to be pumped out.
Mid and West Wales Fire and Rescue were called to a small number of "very minor" flooding incidents overnight, including at a butcher's shop in Lampeter and at properties in Milford Haven and Swansea.
North Wales Police also reported a small number of very minor problems, but nothing significant.