Traces of heating oil or diesel have been detected in the sewerage network in Ballybofey.
Donegal County Council has confirmed that the like source would appear to be the southern side of the Donegal Road from Ard Mac Carron to Townview Heights & Blackrock Drive.
All residents are being asked to please check the condition of their oil tank and boiler and all connections and pipework linking the two.
Any leaks detected should be repaired as a matter of urgency.
