The Minnesota Department of Health says five cities’ public water supply systems will be re-analyzed because of possible misconduct by a lab employee.

The department said Tuesday an internal review found a longtime employee in the Public Health Laboratory was not recalibrating an instrument. That calls the reliability of some water testing data into question.

The employee has been put on leave during an investigation. The Health Department says only one employee was involved and that there is no immediate public health risk.

Health Commissioner Ed Ehlinger says top priority will be given to re-analyzing public water systems. The group includes Edina, St. Louis Park, Spring Park, Kasota and Brooklyn Center, as well as several private drinking wells in Washington County and private wells near a landfill in Wright County.