Private group water schemes in ten counties failed safety tests for E.coli last year, according to a new report from the Environmental Protection Agency (EPA). Today's top videos STORY CONTINUES BELOWThe agency also examined approximately 1,600 registered private water supplies serving locations such as schools, businesses and nursing homes. While most strains of E.coli are harmless, certain types can cause serious illness and food poisoning if consumed through contaminated drinking water. Drinking Water. Pic: Getty ImagesUnder Irish law, operators of private water supplies are responsible for ensuring the water they provide is safe and complies with drinking water regulations.