The order covers businesses and residences along FM 1764 from I-45, west to the city limits, including the Painted Meadows, Westwood Circle and Prairie Knoll subdivisions.
A city spokesperson said water was possibly contaminated after a contractor broke a water main, potentially letting dirt into the line.
Water used for drinking, cooking and making ice should be brought to a rolling boil for two minutes and then cooled prior to use. In lieu of boiling, residents can also purchase bottled water.