Proposed revised sampling protocol for FSMA compliance

Proposed Food Safety Modernization Act water standards have recently changed, including the number of samples to use when testing irrigation water for fresh produce.

The proposed Food Safety Modernization Act (FSMA) is the most sweeping legislation regarding raw agricultural products in 70 years. Recently, the FDA published revised rulemaking in a number of areas. One area that was revised significantly was the number of samples to use when testing irrigation water for fresh produce.

To help make better sense of the various aspects of this standard, Michigan State University Extension will be publishing a number of short articles that will break down the standard and allow for understanding. Each article is a piece of the rule. All the articles must be taken together for a fairly comprehensive understanding of what is proposed for water.

Recall that the act classifies two types of water used in the field: agricultural water and indirect water. If water comes into direct contact with the edible portion of a plant, it is considered agricultural water. If a grower uses overhead sprinklers to irrigate a lettuce field, it would be considered agricultural water. The second type of water is called indirect water. In this case, the water would not come into direct contact with the edible portion of the plant. If drip tape under plastic is used to maintain tomato plants, this would be considered indirect water.

Under FSMA, testing is only required for agricultural water. How often a grower needs to test irrigation water that will be used as agricultural water is determined by its source. Surface waters are proposed to be tested at least five times per year, as close to harvest as you can, but not all at the same time. Well water is proposed to be tested four times the first year, and if the samples meet the standard of a geometric mean of 126 colony forming units (CFU) per 100 milliliters, then once annually after that.

For surface waters, annual test results are aggregated over the last four years to determine a Standard Theoretical Value (STV) and geometric mean. If a grower’s values for the five samples in a given year don’t deviate more than half a log from the geometric mean and STV, then they continue to use the water as they have always done. If there is a deviation of half a log or more, the baseline is recalculated using the last four years’ data points. If a grower’s baseline exceeds the threshold, the grower needs to take measures to mitigate the potential contamination Indirect water is not required to be tested, regardless of the source.

This discussion is not a comprehensive look at the changes to FSMA in the proposed revisions or even in the changes to the water quality section in fresh produce. I encourage interested individuals to take time to educate themselves about the revisions and comment. You can submit comments online. Comments can also be written and faxed to the FDA at 301-827-6870 or mailed to:

Division of Dockets Management (HFA-305)
Food and Drug Administration
5630 Fishers Lane, Room 1061
Rockville, MD 20852

Read more about the FSMA rule and how to comment on the proposed rule. If you have specific questions about the produce rule or have difficulty tailoring GAPs to your farm, contact the Agrifood Safety Work Group at or 517-788-4292.

Additional articles in this series:

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