How does a city as large as Houston suffer such a water plant issue?

Houston's boil water advisory has been lifted and not a moment too soon for the more than 2 million residents affected.

PREVIOUS: Houston boil water notice lifted after testing

So many people are asking how is it possible for a city as large as Houston to have two transformers malfunction leading to a power failure, low water pressure, and a potential water crisis. Well, Houston Mayor Sylvester Turner says he wants that answer as well.

"As much as we rely heavily on equipment, every now and then that equipment will fail," Mayor Turner said. 

RELATED: What led up to Houston's boil water notice

However, that isn’t stopping Mayor Turner from wanting an investigation into how a transformer at the East Water Purification Plant blew out Sunday morning, and then so did its backup. 

"Why they malfunctioned I don’t know," the mayor added. "I have ordered a diagnostic assessment to see exactly what happened and how can we mitigate it from happening in the future." 

The mayor points out Houston's population is growing and maintenance of the plant is likely needed.

"We need more enhancements on our infrastructure to sustain our growth," Mayor Turner said. "The reality is if we don’t address infrastructure there will be even more failures. If you don’t make repairs on your home sooner or later something’s going to break down."

BACKGROUND: Boil water notice issued for large part of Harris County, Houston area

The boil water advisory caused a number of surgeries to be rescheduled, including 15 colonoscopies within Harris Health System, and the possible water contamination shut down several school districts yesterday and today, affecting thousands of parents. 

"Because I work, and I didn’t know what I would do with my kids, but my sister-in-law helped me," said mom of three Rosa Camacho

"My son is in high school now. I feel sympathy for those who have younger kids. I’ve been there. Not anymore," added Houston mom Venice Elder. 

MORE: What does a boil water notice mean? What do I need to do?

Although the power failure made it possible for contaminants to make it into the water supply the mayor says all 29 samples sent to the state came back negative for any bacteria or contaminants.

"Quite frankly for the city of Houston the water has been good since day one, but there is a regulatory process that’s put in place to protect the public safety. We went through the process," Mayor Turner said. "We tried to do it as quickly as we could...I certainly want to apologize to schools that had to close, businesses that were impacted, elective surgeries that had to be postponed."