It was originally built in the 1980 as a fill-in relay for UHF analogue colour television serving all of those settlements.

The "Transmission Gallery" site claims[1] that the Efail Fach transmitter re-radiates the signal received off-air from Cilfrew television relay station near Neath, itself a repeater of Kilvey Hill at Swansea.

When it came, the digital switchover process for Efail Fach duplicated the timing at the Kilvey Hill parent station, with the first stage taking place on Wednesday 12 August 2009 and the second stage was completed on Wednesday 9 September 2009, with the Kilvey Hill transmitter-group becoming the first in Wales to complete digital switchover.

After the switchover process, analogue channels had ceased broadcasting permanently and the Freeview digital TV services were radiated at an ERP of 2 W each.

The UK's digital switchover commenced at Kilvey Hill (and therefore at Efail Fach and all its other relays) on 12 August 2009.