The notice was issued to customers in Point Dume, Encinal Canyon, and anyone inside the area bordered by Westlake Village, the Ventura County line, Malibu and Corral Canyon.
Affected customers should use bottled water or boil tap water for one minute before drinking it, brushing teeth and cooking.
The notices were issued after firefighting efforts resulted in a significant loss of pressure to the district water systems.
Boiling water helps kill bacteria.
City News Service contributed to this report.