Feed the Future
This project is part of the U.S. Government's global hunger and food security initiative.

Postharvest Water in the Food Safety Modernization Act

Postharvest water, the second type of agriculture water listed in the Food Safety Modernization Act (FSMA-Produce Safety Rule), includes water used in produce movement, rinsing, cooling, ice-making, postharvest fungicide, handwashing, cleaning sanitizing surfaces, and other related activities. Postharvest water can be contaminated with human pathogens, after which the water can contaminate (via cross-contamination) fruits and vegetables during the above-listed activities.

FSMA specifies that all agricultural water must be safe and of adequate sanitary quality (no detectable generic E. coli based on a 100ml water sample) for its intended use. Therefore, managing the quality of postharvest water; a) at the start (use potable water) of the use, and, b) during the use (reduce cross-contamination risks), using physical or chemical treatments, is very important to reduce contamination risks. Materials used to treat postharvest water (e.g., sanitizers) that contact produce or produce-contact surfaces must be registered by the EPA for that use. Growers must follow the product label; the label is the law.

FSMA states that if public water supply (such as municipal drinking water) is used, growers do not need to test the water source as long as they have Public Water System results or a current water supply certificate of compliance that the water meets requirements of the Safe Drinking Water Act, or that it is free of detectable generic E. coli in 100 mL of water. However, it is important to notice that if public water is held in containments open to the environment prior to use, it would be considered equivalent to untreated surface water, and it would not be suitable for use as postharvest water, as untreated surface water must not be used for postharvest uses. FSMA requires that untreated groundwater (well water) must be tested during an initial year and annually thereafter. The layout is as follows:

  • Initial year: four times (or more) during the growing season or over a period of a year and, based on these results, determine appropriate use.
  • Subsequent years: one time (or more) during the growing season or over a period of a year. Single-pass water must have no detectable generic E. coli/100ml in the water sample. However, if the results of the tested samples in subsequent years exceed the water quality standard (no detectable generic E. coli/100ml), the number of samplings must be increased to four times (or more) per growing season or over a period of a year.

There are many factors that impact postharvest water quality including; a) pH: some sanitizers (e.g., chlorine) are most effective at a specific pH. Therefore, the pH must be monitored using pH test strips, handheld pH meters and titration kits during the use. The pH must then be adjusted using an approved food grade product, such as citric acid or acetic acid, as needed. Second, temperature is important, as it can impact the effectiveness of sanitizers. Differences between the temperatures of harvested produce and postharvest water can cause infiltration (for example, apples, cantaloupes, mangoes and tomatoes are susceptible to infiltration), and this can introduce pathogens to the interior of the produce if the water is contaminated. Temperature can also impact the health of the workers. If postharvest water temperature is too high and pH is too low, toxic chlorine gas may be formed and become a health hazard. Therefore, FSMA requires that the temperature of postharvest water must be monitored using properly calibrated thermometers to minimize potential risk. Third, turbidity (the level of water cloudiness) reduces the effectiveness of sanitizers and is an important indicator to when to change postharvest water. FSMA requires monitoring the quality of postharvest water. Turbidity can be monitored using turbidity meters. 

FSMA requires that used/waste water (from postharvest activities, handwashing, etc.,) must be disposed properly according to EPA regulations, so it does not contaminate produce, food-contact surfaces, agricultural water, etc. Standard operating procedures for key water management should be developed. Monitoring must be implemented. Corrective actions must be taken when monitoring indicates incompliance with FSMA requirements. With regard to recordkeeping, FSMA requires that all records (findings of the inspection of the agricultural water system, results of any analytical tests, antimicrobial product use, monitoring and corrective actions, etc.) must be kept.

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