Houston Boil Water Notice: HISD, several other districts to remain closed on Tuesday

"We've been a bit stressed out. Because it is a bit of a distraction, especially when we're expected to be at the office and asking for accommodations is always a bit intimidating," said HISD parent Tayyaba Ramirez. "Hopefully, everyone's employer understands, because I don't have a choice."

For the second day in a row, parents are facing another last-minute school day off and how to work around it.

LIST: School districts closed on Tuesday due to Houston boil water notice

"Nobody wanted the transformers to fail. Nobody wanted the situation where you're coming off the holidays, and then you're confronted with this situation," said Houston Mayor Sylvester Turner.

The boil water advisory, which began Sunday night, is due to a pair of transformers malfunctioning at the East Water Purification Plant. That plant services all Houston except for Kingwood and Clear Lake.

"One was the backup to the other," said Turner. "It was just one of those unique circumstances."

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Some question why generators didn't solve the problem.

"We did have generators. But when the transformers failed to operate, it prevented the generators from being connected in order to provide the additional power," Turner said.

The power was down for about two hours Sunday, which caused the water pressure to drop and that can cause contamination.

"Generally, though when you don't see growth or contamination in the first four to six hours, it's highly unlikely that you'll see it later on," Turner said.

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The city has found no signs of contamination. 

The mayor says the advisory to boil water was out of an abundance of caution.

Turner says not long ago CenterPoint Energy told the city nothing more needed to be done to backup the system at the East Water Purification Plant.

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"We're doing a complete diagnostic assessment, based on what happened, to see how we can mitigate it from happening again," he said.

Turner says he's learned one thing in his seven years as mayor.

"Stuff happens," he said. "Whether I like it or don't like it, stuff does happen."