Research work evaluates evidence of microbes in some public water supply wells 

News Release
03/20/2019

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Research work evaluates evidence of microbes in some public water supply wells

Findings will be used to evaluate and address potential public health risks

In an ongoing evaluation requested by the 2013 Minnesota Legislature and shared with stakeholders this week by the Minnesota Department of Health (MDH), scientists report finding evidence of viruses, bacteria and protozoan parasites in water from some of the state’s public water supply wells.

While health officials do not see patterns of illness within the state population that would suggest a widespread threat from pathogen contamination of well water, the findings suggest a need for further examination of the issue. More information is needed to determine how and when pathogens enter the wells and whether there may be a health risk for people drinking the water.

The project was funded through the state’s Clean Water Fund. According to Minnesota Commissioner of Health Jan Malcolm, the findings demonstrate the value of that fund as well as the importance of continuing the strong and proactive partnership among state and local officials working to protect Minnesota drinking water.

“Safe drinking water is essential for Minnesota’s health and prosperity, and we are fortunate to have a strong team of local and state partners working to catch potential threats early,” Commissioner Malcolm said. “More work is needed to determine how best to respond to these latest findings, and I’m thankful that Governor Walz’s budget plan includes proposals to strengthen our work on drinking water protection.”

The Governor’s budget plan directs additional resources from the Clean Water Fund to conduct research into emerging threats facing drinking water. The plan also includes a service connection fee adjustment that amounts to a penny a day per connection. That fee adjustment will ensure continued state technical support for drinking water systems around the state as they work proactively to prevent contamination of their water.

The wells involved in the MDH evaluation project were from public water systems around the state. Department staff have been notifying system owners with the highest-risk wells, discussing results and next steps.

MDH has detected only five outbreaks of waterborne illness caused by microbial contamination of drinking water in the past 25 years. However, most illnesses do not occur as part of outbreaks, and it is unknown how many of these illnesses not associated with outbreaks may be due to drinking contaminated water. This project helps state and local officials better understand the threats facing Minnesota drinking water. It can also help health officials develop strategies to minimize risk.

The study found microbes in some systems on more than one occasion, but was not able to determine how they got into the wells. Microbes typically can get into wells when feces from leaky sewer lines, septic systems or other sources get into the groundwater or directly into the well. If water contaminated in this way is not adequately treated, people drinking it may become sick.

The scientists conducted the work in two phases over several years. As part of that process, MDH sampled 145 public drinking water supply wells. Most wells were sampled every other month for one or two years. Most of the sampled wells (70 percent) had at least one detection of pathogen genetic material. However, only 22 percent of overall samples had a detection. This suggests pathogen occurrence is irregular and is likely only under certain conditions.

Until additional work is done, MDH has no specific protective recommendations prompted by the findings so far. However, consumers with concerns about potential microbial contamination have several options, including using bottled water, boiling water used for food preparation and drinking, or installing a reverse osmosis water filter.

More generally, MDH recommends both public and private water systems continue to maintain their wells and conduct routine testing of their water supply, and to follow recommended procedures for operating and maintaining septic systems or other contaminant sources.

More information is available on the MDH Groundwater Virus Monitoring Study web page.

-MDH-


Media inquiries:

Doug Schultz
MDH Communications
651-201-4993

doug.schultz@state.mn.us