Nov. 28 (UPI) -- The City of Houston has issued a boil water notice to its millions of residents after water pressure in its main system dropped over the weekend, prompting several school districts to cancel classes for Monday.
City officials said in a statement Sunday evening that the pressure drop is attributed to a power outage at its East Water Purification Plant that began at 10:30 a.m.
Pressure has since been restored to its 2.2 million customers but the boil water notice was issued to ensure all harmful bacteria and other microbes potentially in the water were destroyed.
"We believe the water is safe but based on regulatory requirements when pressure drops below 20 psi we are obligated to issue a boil water notice," the office of Houston Mayor Sylvester Turner said in a statement.
Samples were submitted Sunday night to the Texas Commission on Environmental Quality for approval, but the city will have to wait at least 24 hours before it can rescind the boil water notice, he said.
"The earliest would be tomorrow night or very early Tuesday morning," he said.
The city's largest Houston Independent School District of more than 194,000 students announced late Sunday that it will remain closed Monday following the Thanksgiving weekend due to the boil water notice.
The school districts of Spring Branch, Aldine, South West Schools, Pasadena, YES Prep and Varnett Public School also said their classes would be closed Monday.
Alief ISD, Clear Creek ISD, Crosby ISD, Fort Bend ISD and others said they would remain open.
"All CFISD campuses will be open on Monday," Cypress-Fairbanks ISD, which serves more than 114,880 students, said in a statement. "CFISD campuses that are affected by the City of Houston boil notice will have bottled water, meals that can be warmed without water and additional hand sanitizers.
"Toilet flushing is not affected."