by Bryce Gray, originally posted on September 7, 2016

The water boil advisory that affected a reported 85,000 customers across St. Louis County may have been triggered by a vehicle’s running into a pole near Missouri American Water’s largest treatment facility on Tuesday.

The advisory, issued as a precaution to ensure water safety, was put into effect Tuesday morning and lifted about 8:30 a.m. Wednesday. Residents were urged to boil water for three minutes prior to consumption or use in cooking.

The water company announced on its Facebook page that “the water quality tests have confirmed the water is safe for consumption.”

Ameren Missouri representatives said that a vehicle hit an electrical pole at Pritchard Farm and Creve Coeur Mill Roads “causing a momentary outage” at Missouri American’s water treatment plant on Hog Hollow Road.

Police representatives in Chesterfield and Maryland Heights were unable to verify whether that car accident occurred.

Although a spokeswoman said technological improvements to Ameren’s grid were able to redirect power and avoid outages to other customers, the nearby water treatment facility was affected by the hiccup.

Missouri American spokeswoman Christie Barnhart characterized the water company’s loss of power as a “blip” lasting only a second or two.

But that blip had profound repercussions, causing water pressure to dip below safety thresholds at which untreated groundwater can potentially infiltrate pipes. Though Barnhart indicated that no contamination of the water supply was detected, that temporary loss of pressure prompted Missouri American to issue a precautionary boil advisory that blanketed a sizable portion of St. Louis County.

Drinking fountains were sealed and sales of bottled water soared Tuesday after customers were notified of the advisory.

Barnhart said that the initial wave of boil advisory calls went out about two hours after the loss of power, after the utility was able to gauge the extent of affected areas.

Barnhart said that the water company was conducting internal investigations into the incident. She said she was unaware of the reported car accident.

The facility uses dual power feeds “to mitigate power interruptions,” Barnhart said. But the power loss still disrupted the pump that sends treated water into distribution pipes and the facility’s diesel generators would not have been able to respond quickly enough to the short-lived outage, Barnhart said.

She said different backup generators “are currently being designed and are scheduled for construction in early 2017.” Those will reportedly have an automatic transfer switch to guard against fleeting losses of power.

When reached for comment, Tom Bastian, director of communications for the Missouri Department of Natural Resources, could not confirm whether the agency was reviewing the incident, but suggested that it was a matter for Missouri American to address internally, since they issued the boil advisory voluntarily. Bastian also did not comment when asked whether the incident exposed potential vulnerabilities of the public water supply.

The boil advisory on Tuesday was notable for how widespread it was. The last advisory of a similar magnitude happened in 2006, when 250,000 customers were affected by another instance of low pressure caused by a power outage, according to Barnhart.