6,500 properties are without water due to NI Water workers taking industrial action over pensions.
More properties may also be disrupted, NI Water has warned.
The areas affected include: Areas that may be affected include:
Ederney, Kesh, Lack, Castlederg, Killen, Killeter, Spamount, Irvinestown, Dromore (Tyrone), Drumquin, Omagh (rural) and Trillick.
Greencastle, Mountfield, Sixmilecross, Carrickmore, Glenhull, Loughmacrory, Rousky, Beragh, Garvaghy, Eskragh and Seskinore.
Claudy, Dungiven, Feeny, Gortnahey, Park.
Ongoing Water Supply Disruption Issues
In a statement NI Water said: "NI Water fully recognises this is a frustrating experience for our customers, and can assure them we are doing everything possible to restore water supplies.
"NI Water has mobilised all resources at its disposal to deal with this latest incident, however, due to the limited resources available to us, as a result of industrial action, our response has been restricted.
"Unfortunately though, with 26,000kms of watermains, 15,000kms of sewers and literally thousands of pumping stations and treatment works to monitor, it was virtually inevitable there will be interruptions to services to our customers.
"NI Water remains on high alert with a Major Incident regime in place and we are committed to continued engagement with Trade Unions in an effort to resolve this dispute."
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