Minimizing Risks: Use of Surface Water in Pre-Harvest Agricultural Irrigation

Irrigation water can act as a vector, or carrier, that can transport or spread pathogens to crops, where they have the potential to cause illness (CDC, 2018). Decisions to treat irrigation water can be driven by buyer requirements, for product marketing or branding, or because the water quality exceeds the FDA Food Safety Modernization Act (FSMA) regulations or the Leafy Green Marketing Agreement (LGMA) standards for generic Escherichia coli (E. coli). For example, the quality of surface waters may be more impaired or have higher pathogen contamination compared to groundwater (FDA, 2018). This is because they are directly exposed to external influences and therefore may require treatment. To ensure irrigation water is at a quality sufficient to meet grower needs, it is important to understand how water quality affects treatment methods and associated challenges and solutions. If the quality of the water source is unknown, there are many labs recommended by the Arizona Department of Health Services that offer U.S. EPA approved testing methods. Links to testing labs, EPA registered sanitizers, and approved testing methods are provided at the bottom of this fact sheet. This publication is a general overview of water quality and common treatment methods.
It is the first of a series covering specific treatment options for pre-harvest agricultural irrigation such as chlorination, Ultra Violet (UV), and peroxyacetic acid.