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Foodborne outbreaks have been traced to contaminated irrigation water. The use of contaminated water to irrigate crops by surface, sprinkler, or conventional drip irrigation may pose a public health hazard due to the potential presence of pathogens. It is immediately apparent that crops that come in direct contact with contaminated irrigation water can become contaminated. Thus, this study assessed a subsurface irrigation system quantitatively with romaine lettuce in terms of crop contamination when microbial-contaminated water was used for irrigation. A cropping system for bottom watering pots at the greenhouse and a subsurface drip irrigation (SDI) system commonly used for lettuce production in Arizona was modeled with the well-known software, HYDRUS 2D/3D, to ensure that the soil surface does not become wet and consequently contaminated. Experiments were conducted during the full growth cycle of romaine lettuce to fulfill the study purposes. Escherichia coli ATCC 25922 and bacteriophage MS2 were used as surrogate microorganisms for this study. No microbial contamination of produce occurred in romaine lettuce irrigated with contaminated irrigation water utilizing bottom watering pots. Maintenance of a dry soil surface appeared to avoid crop contamination in subsurface irrigated lettuces. Subsurface irrigation systems with proper management can be excellent strategies to not only conserve water resources but to reduce or eliminate contamination of leafy green vegetables when harmful microbes are present in the irrigation water. In the second aspect of this study, microbial contamination of lettuce plants irrigated by surface irrigation was investigated to aid in the development of irrigation water quality standards for enteric bacteria. Surface irrigation was evaluated with the use of Escherichia coli O157:H7 transfer data to the plants. The Beta-Poisson model was used to estimate the microbial risk of annual pathogen ingestion. The risk of infection was found to b

The increasing threat of water scarcity throughout the world has led to the implementation of potable wastewater reuse. During potable wastewater reuse, final treated wastewater effluent is purified to drinking water quality. This is performed to augment current drinking water sources. However, treated wastewater effluent is of degraded quality when compared to conventional drinking water sources, therefore extensive treatment and quality monitoring is required for the protection of public health. Removal of pathogens, particularly viruses, is a major concern during wastewater reuse, as sewage is a significant source of enteric pathogens. Viruses are the smallest of enteric pathogens and have physical attributes which allow for persistence in the environment for extended periods of time while maintaining viability. Therefore, strict requirements pertaining to virus removal during wastewater reuse are enforced. Treatment facilities are required to demonstrate the capability of different treatment technologies implemented for virus removal. This is largely done by the spiking of laboratory propagated MS2 coliphage, which is recommended by the National Water Research Institution Framework for Direct Potable Reuse (2015). Additionally, if membrane processes are implemented, they must undergo continual monitoring ensuring membrane integrity, which is performed by spike evaluations as well as the use of non-viral surrogates such as conductivity and total organic carbon. However, spiking coliphages can quickly become cumbersome at full-scale facilities. Advances in virus detection technology has facilitated the potential use of naturally occurring indicator viruses as a means of evaluating system performance. Wastewater is a rich reservoir of viruses, with non-human viruses greatly outnumbering viral pathogens. These abundant non-human viruses can be utilized as indicators of viral pathogen fate, allowing for continual monitoring of virus removal performance by a variety o