Hurricane Harvey left hundreds of communities in southeast Texas without safe drinking water. At least 45 water systems are shut down, and 171 areas have issued boil water notices. But Houston is not on that list, despite significant flooding at one of its water plants.

"The filters are the life blood of the plant. If you lose filtration, there's nothing you can do," said Drew Molly, the facility's assistant director.

For the first time, Houston officials are revealing just how close they came to a potential drinking water crisis. Harvey flooded the northeast water purification plant last week. CBS News has learned the city's drinking water system was hours away from failure. The machines that kept its water filters clean were themselves under water, reports CBS News' Bianna Golodryga.

"At the peak of nervousness, were you more in the engineer mode, or in prayer mode?" Golodryga asked.

"I was in prayer mode. I was in survivor mode," Molly said.

Houston Mayor Sylvester Turner said the plant shutting down would have been a huge blow to a city already in crisis.

"You can't notify people to boil your water and tell them at the same time – but the water is safe," Turner said. "That doesn't work. … For the city of Houston and for our region, this plant simply could not fail."

To buy more time for the filters, Molly and his team slashed how much clean water the plant was pumping out. Contractor Peck Boswell then brought aqua barriers and pumps to get all the floodwater out. Without them, Molly said they would have had to shut the plant down.

The plant is functioning normally again, helping to provide clean water to some 2.2 million customers. But not everyone in the Houston area gets drinking water from the city. Some like Leo Ramirez and Adriana Betancourt rely on private wells.

"I actually had somebody come out and drill the hole," Ramirez said.

Their house was under three feet of flood water, a stew of countless toxins and pollutants. They allowed CBS News and the county health department to test their well water. Both results suggest the presence of fecal matter, with some form of E. coli and other bacteria.

"What does this tell you about going forward and rebuilding?" Golodryga asked.



"Well unfortunately, this is our house," Ramirez said. "We're going to rebuild, and try to keep moving forward."

Starting Tuesday, Harris County health officials will be setting up locations where residents who rely on well water can bring in samples to be tested. With chronic flooding and major storms now the reality in Houston, Mayor Turner is encouraging all residents to get their drinking water from the city.