Quach, EmilyAquaponics (APs), a soilless production system, integrates aquaculture and hydroponics to provide local fresh produce while conserving natural resources. The absence of soil in APs eliminates one potential food safety risk present in typical soil-based production systems, but APs may become contaminated from a variety of sources. Escherichia coli TVS 354 long-term survival was evaluated in bench-scale, deep-water APs units. In addition, pathogen presence on basil and lettuce at the time of harvest and changes in the population density of mesophilic aerobic bacteria in APs were measured. Results showed E. coli populations significantly decreased 24 h post-inoculation in water samples and remained undetectable by day 1 post-inoculation. Lettuce harvested on day 60 had detectable E. coli on lettuce leaves and roots at harvest. These results provide new insight on E. coli survival in harvested plants, indicate potential risks for foodborne illnesses, and unreliability of water testing as a monitoring tool.enThesisEnvironmental scienceAgricultureMicrobiology