As summer swimming season approaches, the importance of assessing water quality cannot be overstated, especially following significant incidents like the sewer line collapse in Maryland, which spilled over 360 Olympic-sized swimming pools of wastewater into the Potomac River. This event serves as a stark reminder of the risks associated with fecal pollution in natural waterways, which can lead to illnesses caused by waterborne pathogens. Current testing methods typically focus on E. coli for freshwater and Enterococcus for saltwater as indicators of contamination. However, these methods have limitations, as highlighted by environmental microbiologist Kelly Reynolds from the University of Arizona. A recent study by Sandra McLellan at the University of Wisconsin–Milwaukee proposed a more accurate DNA-based testing method, revealing that 46% of water samples contained fecal pollution, compared to only 18% detected by traditional tests. To ensure safety, the EPA recommends that E. coli levels should not exceed 235 colony forming units per 100 milliliters of water, as higher concentrations significantly increase the likelihood of illness. Experts suggest avoiding swimming for 24 hours after light rain and 48 hours after heavy rainfall to minimize exposure to contaminants, emphasizing the importance of checking water quality advisories before swimming.