In a report published in published yesterday in Morbidity and Mortality Weekly Report, during July–September 2023, an outbreak of Shiga toxin–producing Escherichia coli O157:H7 illness among children in Utah, caused 13 confirmed illnesses; seven patients were hospitalized, including two with hemolytic uremic syndrome. Local, state, and federal public health partners investigating the outbreak linked the illnesses to untreated, pressurized, municipal irrigation water (UPMIW) exposure 12 of 13 ill children reported playing in or drinking UPMIW. Clinical isolates were genetically highly related to one another, and environmental isolates were from multiple locations within the city UPMIW system. Microbial source tracking, a method to indicate possible contamination sources, identified birds and ruminants as potential sources of fecal contamination of UPMIW. Lehi, UT, installed an upgraded drinking water system in 1989 and established its UPMIW system by converting its previous drinking water system to a UPMIW system. Because the city also uses UPMIW for fire suppression, it remains available year-round. However, its use is only encouraged during landscape irrigation season, usually mid-April through mid-October. Although UPMIW is not intended for recreation, all but one child with UPMIW exposure in this outbreak reported some kind of play in the water. This outbreak demonstrates the need for ongoing educational efforts. @ https://www.cdc.gov/mmwr/volumes/73/wr/mm7318a1.htm#:~:text=In%202023%2C%20at%20least%2013,two%20with%20hemolytic%20uremic%20syndrome.