Uisce Éireann leak detection crews are continuing work today in the Keelogs and Druminor areas of Buncrana in search of a significant leak.
The leak is putting pressure on the daytime water supply, with night-time restrictions in place to allow reservoirs to recover.
Restrictions will run from 11pm tonight until 7am tomorrow to help ensure a normal supply for homes and businesses during the day.
Customers are being asked to use water carefully and report any leaks.
Simple measures such as taking shorter showers, using a basin in the sink and fixing dripping taps are also being encouraged.
