Following are locations where the Fahey surname was found in Griffiths Valuation in Ireland between 1848 and 1864. Griffiths was a list prepared for tax purposes of those who owned or rented property. The numbers are the number of times there were entries for the surname in that location.
Cork City (Co. Cork) 1
Dublin City (Co. Dublin) 1
Limerick City (Co. Limerick) 7
Offaly (at that time Kings County) 4
Please note this list doesn't include entries for the Fahey surname variations in Ireland of Fahy and Vahey.