"Stuff happens, whether I like it or don't like it," Mayor Sylvester Turner said on Monday.
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According to Turner, a transformer at the water plant failed, as well as the backup transformer. Generators never kicked in.
The city has a long-standing $56 million contract with NRG Energy Services to have backup power generation equipment at the East Water Purification Plant.
"Well, 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.
NRG told 13 Investigates the problem was with the two city-owned transformers and was not on its end.
PREVIOUS REPORT: Houston boil water order resulted from ground trips at power plants
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"We do know that the two transformers malfunctioned. One was a backup to the other. It was just one of those unique circumstances in which you have these transformers that malfunction and then you have the backup that malfunctioned," Turner said.
ABC13 asked how this could have happened, but it appears even the city doesn't have the answer.
"(We're) working through the issues to understand exactly what the failure was to make sure we have every step in place that we make sure this doesn't happen again," Carol Haddock, the Houston Public Works director, said Monday evening.
Turner says a diagnostic assessment will be done to see what went wrong.
SEE ALSO: Multiple Houston area schools to remain closed for second day as city is under boil notice
He added CenterPoint Energy did an assessment of the same plant where the transformers malfunctioned, causing this citywide boil water notice that impacted 2.3 million people.
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"That there was not much more we needed to do to back up this system...that we had the transformer backing up the transformer. We had generators in place...that the system was hardened. But apparently, it was not hardened enough" Turner said.
Public works said the plant has been undergoing a more than $23 million improvement project that started in June.
ABC13 reached out to CenterPoint Energy, which, through a spokesperson, told ABC13 that it's looking into the mayor's remarks of an assessment done by the company. The utility would get back to us.
What happens next? City officials said they are testing the water across the city, collecting samples that will be submitted to the state. They are now at a City of Houston lab and must be observed and tested.
These samples have to sit for 18 hours to see if anything grows. The hope is that there will be an all clear by 3 a.m. Tuesday. Texas Commission on Environmental Quality has authority to lift the notice.
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