Dozens of north Harris County residents are on their 12th day without drinkable water.
Water pressure was restored an hour after the break, but the city had been testing the water for bacteria for the past two days.
City officials said the mandatory notice was issued after a water main break at East Boulevard and X Street caused the system pressure to drop to 20 psi.
Residents in Montgomery Co. MUD No. 139 were told thieves took enough electrical equipment to force the plant to shut down, leading to a boil water notice on Tuesday.
The City of Tomball said residents in the impacted area can resume using water normally.
Residents in the impacted area can resume using water normally, but MUD 151 issued a reminder that Fort Bend County is still in stage one of its drought contingency plan.