https://phys.org/news/2018-06-treatment-contaminants.html

According to the results of the project, the purification process was effective in removing pathogenic microbes, but small amounts of chemical substances were identified in the artificial groundwater.

"The observation raises questions about the health risks caused by chemical contaminants. However, based on a risk assessment, none of the individual chemical contaminants exceeded the tolerable daily intake limit," explained principal investigator Päivi Meriläinen of Finland's National Institute for Health and Welfare.