More than 2 million people across Houston faced a boil water order Monday and schools were shut down after a power outage disrupted the city's water system.
Water pressure dropped below the Texas Commission on Environmental Quality's required minimum Sunday at the East Water Purification Plant, authorities said.
"There is no evidence of water contamination," Mayor Sylvester Turner tweeted. He said that when the water pressure drops precipitously "there is a regulatory requirement to issue a boil water notice even if we believe the water is safe to drink."
Workers began collecting samples Monday and were schedule to draw two complete sets to send to a lab for processing. It was unclear when the water could be declared safe to use. Turner said the boil order could be lifted 24 hours after the city is notified the water is safe.
Children, seniors vulnerable to bacteria
The public was advised to bring water to a boil for at least two minutes - and then letting it cool - before using it for drinking, cooking, bathing, and brushing teeth. Children, seniors, and people with weakened immune systems are particularly vulnerable to harmful bacteria, but all water customers should follow these directions, the city said in a statement.
Water for ice makers and water dispensers from refrigerators should not be used until the water is declared safe, the city said.
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Gov. Greg Abbott said his office had been in contact with Mayor Turner to offer support. Abbott's office was working to fulfill the city's request for help with rapid turnaround of water sample results, Abbot said.
"Together, we will ensure our fellow Texans are supported while the city's water supply returns," Abbott said.
The Houston Independent School District extended the Thanksgiving break at least one day, closing schools for its more than 210,000 students and almost 12,000 teachers.
The district said it "will closely monitor the situation and provide additional updates regarding operations."
This article originally appeared on USA TODAY: Houston issues boil water advisory to over 2 million, closes schools