Bridging the GAPs: Approaches to Treating Water On Farms

In terms of assessing water quality, as FDA reconsiders the requirements in Subpart E, growers who are currently testing their water should continue to do so. If not testing, growers may consider initiating a testing program to better understand their water quality, and if not already doing so, should follow Good Agricultural Practices (GAPs) to protect and maintain quality. As written in the rule, growers should identify and reduce risks by developing water management strategies, such as a water system survey. This helps to prioritize those areas of concern within the system that could pose a threat to pathogenic contamination.

Corrective Measures

If a grower meets the above criteria, the water can be used as intended for growing purposes. However, if the water does not meet the criteria or exceeds the threshold, the grower can apply the following corrective measures, according to the Produce Safety Rule: 1. Stop using the water and re-inspect the water distribution system for potential sources of hazards. Once corrective actions are applied and verified to reduce the risk of microbial contamination, the water can be used.

2. Apply a time interval for microbial die-off between the last application and harvest, or between harvest and the end of storage and/or removal during activities, such as commercial washing.

3.

Treat the water.

According to the FDA, treating the water may be a viable corrective measure to lower the risk of pathogenic contamination.

Overview of Agr icultural Water Treatment

Why treat agricultural water?

There are multiple reasons why growers may treat irrigation water. Particularly in greenhouse operations, treatment of water may be implemented to prevent biofilm formation. A biofilm is an aggregate or community of bacteria, algae, or a mixture of both, that attaches to a surface and produces an extracellular polymeric substance commonly known as slime. Biofilms can persist in irrigation lines feeding off nutrients meant for plants, thus causing nutritional deficiencies for proper plant growth. Furthermore, biofilms can clog irrigation lines and emitters, impacting pressure and continuous flow. In addition to preventing biofilm formation, treatment of irrigation water may be implemented to improve the microbial quality of the water. Irrigation water can serve as a vector for plant pathogens, as well as human pathogens. While plant pathogens can directly impact plant health, irrigation water is a major source of concern for spreading human pathogens, such as E. coli O157:H7, Salmonella, or Listeria monocytogenes. In addition, treatment of irrigation water may be applied to minimize effects of seasonal variability and unexpected events, such as heavy rainfall. Treatment could also be implemented due to limited or infrequent use of a particular surface water.

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