Bacteria and viruses commonly found in drinking water

Both bacteria and viruses are microorganisms regulated by EPA’s Maximum Contaminant Levels (MCLs) criteria. Viruses are the smallest form of microorganisms capable of causing disease, particularly those of a fecal origin infectious to humans by waterborne transmission; bacteria are typically single-celled microorganisms that can also cause health problems in humans, animals or plants, despite many form’s ability to aid in water pollution control.

https://www.watertechonline.com/wastewater/article/15545721/bacteria-and-viruses-commonly-found-in-drinking-water