Fecal coliform bacteria forces shutdown of one Tucson Water well

A city well in east-side Tucson is out of service until some time next week because of bacterial contamination.

The contamination was found only in a sample of groundwater from the well before the water was treated to remove the bacteria, meaning Tucson Water customers never drank the tainted water, the utility said Tuesday.

Two samples from the well, taken late last week, tested positive for E. coli, an indicator of fecal coliform bacteria in the water. Such fecal indicators are microbes that suggest human or animal wastes could be in the water. Those microbes can cause diarrhea, cramps, nausea or headaches.

The well has since been taken out of service, Tucson Water said. The well lies near Broadway and Camino Seco. It's part of a broader distribution system that receives water from "dozens upon dozens" of wells on the south, east and northeast sides, utility spokeswoman Natalie DeRoock said.

Tucson Water officials said there's no way this water was ever served to people because it was "raw water," water from the well before it's treated. Before the water goes into the city's drinking water distribution system that serves people, it's chlorinated, a process that normally removes contaminants such as E. coli, utility officials said.

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Water from that well is also blended with Central Arizona Project water from the Colorado River before being served to customers, DeRoock said.

For now, utility officials say that in addition to deactivating the well, they "will conduct purging, disinfection, and additional sampling of this well next week to determine the extent and source of the problem."

Once sample results show the water contains no fecal indicators, and once the Arizona Department of Environmental Quality gives its approval, the well will be returned to service, the utility said.

"We anticipate resolving this problem within the next 10 days," the utility said.