Cold plunging has been gaining popularity recently due to its health benefits such as muscle recovery and mental focus. Cold plunging involves emerging the body in 50 deg F for up to 10 minutes in a tank that varies in volume (100 – 1,000 gallons). Despite its popularity, little is known about cold plunge water quality and treatment efficacy. In this study, water from three cold plunge sites in Minneapolis, MN was collected over a 6-month period in addition to one cold plunge tank in Eau Claire, WI. Cold plunge samples were analyzed for pathogens and indicator organisms, including Pseudomonas aeruginosa, Staphylococcus aureus, fecal coliforms, and heterotrophic bacteria. Samples were collected by City of Minneapolis environmental health staff and transferred on ice to the UWEC ENPH lab within 24 hours for analysis. Samples were processed using membrane filtration and plated on different media types including; Mannitol Salt Agar, Pseudomonas CN agar, mFC agar, and Tryptic Soy Agar. Samples were incubated at 35 deg C for 24 - 48 hours dependent on media type. Bacterial colonies were counted and recorded, including negative controls to check for contamination. This project helps understand bacterial levels in cold plunge tanks and could guide future recommendations for best management practices at cold plunge facilities.
