Trethomas is a village in Caerphilly county borough, Wales.
It is situated within the CF83 postcode district, which is within the Caerphilly post town.
CF83 is the only postcode district within the Caerphilly post town.
The Caerphilly post town is within the Cardiff postcode area.
Administrative Ward: Bedwas, Trethomas and Machen
Administrative District: Caerphilly
Country: Wales
UK Parliament: Caerphilly