A clean-up operation is underway in Neath Port Talbot today following heavy rainfall overnight.
Fire crews went to about 20 incidents in four hours and worked through the night to help those affected by flooding, which hit homes and roads.
An elderly woman was rescued when houses were washed out in a street in Baglan, Port Talbot.
The main areas affected were Baglan, Briton Ferry, Neath, Port Talbot, and Port Eynon and Reynoldston in Swansea.
Merthyr Tydfil fire station was also hit by flooding. There are some road closures, including at Langland, Swansea where a pothole has opened up.
Mid and West Wales Fire Service said they worked through the night to help people who were flooded in their homes.
About eight houses in Baglan were washed out.
The rescued elderly woman stayed with a neighbour overnight as firefighters continued to pump out the water.
A spokesman said the busiest time was from 2200 BST to 0200 BST.
Crews were called to pump out water from domestic properties.
Staff from Streetcare Services worked through the night on emergency call-out co-ordinating operations from the CCTV control room at council headquarters on the Baglan Energy Park.
Persistent rain in the early evening, followed by heavy rain from 10pm until 2am, caused flooding problems at several locations including Baglan, Briton Ferry and Sandfields, where drainage systems were unable to cope with the volume of water.
Baglan Road outside the Bagle Brook was closed and a number of homes in Heol Y Nant were flooded due to a blocked culvert.
Briton Ferry Road from the Lodge lights to Hoo Street was also closed and some homes flooded in Briton Ferry.
Head of Regeneration at Neath Port Talbot Council Gareth Nutt said: "Gangs are out today cleaning up debris and checking and cleaning culverts where necessary.
"The situation is being monitored and gangs will remain on standby out of working hours until the weather front has left the area and conditions improve."
South Wales Fire Service said Merthyr Tydfil Fire Station was affected with minor flooding overnight.
Water was leaking through a window and affected all floors. It happened at about 2330 BST.
South Wales Police said part of the carriageway and footpath at Higher Lane, Langland, Swansea, has been closed by the council after a pothole, 4ft 6ins in diameter, opened up.
It happened at about 1740 BST on Wednesday.
Police also said many single track roads on Gower were affected by the rain overnight but that the situation seems to be easing now.
Roads closed due to flooding included the A4118 Gower Road and the A474 at Neath Port Talbot although the A4063 Cymer Road between Caerau Road and Woodlands Terrace re-opened on Thursday morning.
The A48 Pentwyn Baglan Road is also closed in both directions between St Illtyd's Drive and the Pentyla junction (J41) of the M4.
Light rain has been forecast today but is expected to be less intense.