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FSMA Produce Safety Rule Water Requirements: Insights to Get You Organized!

May 18, 2016
Don Stoeckel, Ph.D., Gretchen Wall, M.S., Betsy Bihn, Ph.D.

There has been a lot of talk about the water requirements that are part of the Food Safety Modernization Act (FSMA) Produce Safety Rule (PSR).  This article will help you know what is covered by the requirements, the timing of the requirements, and some key things to help you prepare.  There will be more information coming on the topic, including guidance from FDA.  This article is meant to be an introduction to some of the main parts of the water requirements.  Some of the key terms and phrases are marked in bold; you can expect to see these terms again so now is a good time to start getting used to them.  The main points of this article are:

  • Understanding when water qualifies as agricultural water
  • Microbial quality requirements for agricultural water used during growing activities or during and after harvest
  • Microbial Water Quality Profile: What is it, how many samples do you need to build one, and what resources are out there to help you
  • Options if your agricultural water does not meet microbial water quality criteria

Understand When Water Qualifies as Agricultural Water

The water quality requirements in the FSMA PSR only apply to farms covered by the rule that are using water that directly contacts the harvestable part of the crop during growing activities, or during and after harvest activities.  The language directly from the PSR requires that “all agricultural water must be safe and of adequate sanitary quality for its intended use” (§ 112.41). Agricultural water is defined in part as “water (that is) intended to, or is likely to, contact covered produce or food contact surfaces” and covered produce is defined in part as “the harvestable or harvested part of the crop” (§ 112.3(c)).  It is important to note that food-contact surfaces are also included in this definition, so agricultural water quality requirements will have to be met when establishing cleaning and sanitation programs as well.

Microbial Quality Requirements For Agricultural Water Used During Growing Activities, or During and After Harvest

Different water quality criteria are established for water used during growing activities and for water used during and after harvest. Both are based on testing water for generic Escherichia coli, which is an indicator of fecal contaminationBelow are the requirements. Please note, water used during growing activities can have a limited amount of E. coli present in the water, whereas water used during or after harvest must have no detectable generic E.coli present in the 100 mL water sample.  The next section of this article will outline the specifics about creating a microbial water quality profile (MWQP) and there is an additional worksheet entitled Geometric Means, Statistical Threshold Values, and Microbial Die-Off Rates that describes how to do the associated calculations, but for now, just review the numbers.

  • The requirement for agricultural water used during growing activities is a microbial water quality profile, based on a rolling 4-year sample data set, that has a geometric mean of 126 or less CFU/100 mL generic E. coli and a statistical threshold value of 410 or less CFU/100 mL generic E. coli.
  • The requirement for agricultural water used during and after harvest is no detectable generic E. coli in 100 mL of water. 

Please read the remainder of this article for explanations of those main points, and flexible management options included in the PSR for water that does not meet the E. coli based water quality requirements.

To start, it is important to talk about what is covered by the PSR. The PSR only covers microbiological hazards, so the water requirements only include microbiological testing. Controlling fecal contamination is one key to minimizing produce safety issues, and the test for generic E. coli indicates fecal contamination without the cost of testing for all microbial human pathogens. Again, it is important to be clear about the term agricultural water so here is the exact definition from the PSR.

Agricultural water means water used in covered activities on covered produce where water is intended to, or is likely to, contact covered produce or food contact surfaces, including water used in growing activities (including irrigation water applied using direct water application methods, water used for preparing crop sprays, and water used for growing sprouts) and in harvesting, packing, and holding activities (including water used for washing or cooling harvested produce and water used for preventing dehydration of covered produce).”

Notice a couple of things in that definition. 

  • Agricultural water is used during covered activities on covered produce.  Covered activities refer to activities that are described in the rule (e.g., growing, harvesting, packing, and holding). Covered produce has a specific definition in the PSR, generally, produce that is normally consumed raw and is a raw agricultural commodity.
  • In order to be considered agricultural water, the water must be used in direct contact with the harvested portion of covered produce, or food-contact surfaces (including hands).  Water used in other ways on the farm does not fall under the definition of agricultural water. 

It is also important to understand when the requirements of the PSR go into effect.  For many farms the answer is never.  Some farms are not covered, or they qualify for exemptions or modified requirements. It is important to keep in mind that, even without a legal requirement to follow the PSR, a buyer might demand that a grower follow the provisions in the PSR.  For those subject to the PSR, compliance dates for most provisions begin January 26, 2018 depending on the farm’s business size. An FDA proposed rule would result in extended compliance dates, beginning in 2022, for parts of the PSR dealing with agricultural water (except for sprouts). This gives extra time for sample collection and analysis. See the FSMA Produce Safety Rule Compliance page for more details about compliance dates. 

In addition to meeting the microbial water quality criteria, growers subject to the PSR will be required to inspect their agricultural water systems at least once a year, and to maintain their water sources and water distribution systems. Compliance dates for these practices also will be extended, beginning in 2022, under the FDA proposed rule. It is important to remember (as mentioned above) that “all agricultural water must be safe and of adequate sanitary quality for its intended use” (§ 112.41) so you may have to pay attention to other water quality issues in addition to the presence of E. coli if other risks are identified.

Microbial Water Quality Profile: What is it, how many samples do you need to build one, and what resources are out there to help you

For agricultural water that is used during growing activities, a microbial water quality profile (MWQP) has to be developed.  The MWQP is intended to help a grower make water management decisions using a rolling 4-year data set of results to understand water quality determined through water testing and two statistical calculations:  a geometric mean (GM) and a statistical threshold value (STV). The MWQP is based on at least 4 samples for ground water sources of agricultural water (e.g., protected well), and at least 20 samples for surface water sources of agricultural water (e.g., pond, stream, river) tested for generic E.coli.  Collection of the initial ground water sample set must be done in one year; collection of the initial surface water sample set will have to start at least two years before the water quality requirement compliance dates.

As mentioned earlier, the numeric requirement for agricultural water used during growing activities is an MWQP that has a GM of 126 or less CFU/100 mL generic E. coli, and a STV of 410 or less CFU/100 mL generic E. coli

The terms GM and STV will be new to a lot of people.  Luckily, there are tools available to help do the calculations.  There is a worksheet for those who want to do the calculations by hand (mentioned above), but there is also an online calculator that can be found at the Western Center for Food Safety web site ( Two important take away messages regarding the MWQP are:

  • There are resources available to help you do the calculations and,
  • The E. coli-based requirements do not go into effect for several years (2020 at the earliest) but the development of a surface water MWQP should start at least 2 years before the compliance date for your farm.

Please note, FDA will be publishing guidance to help you implement water testing and the creation of the MWQP.  Until guidance is released, you should not invest in testing towards the development of the MWQP.  If you are already doing water tests to meet buyer requirements or as part of a third party audit, then continue to do that water testing, but do not make significant changes or investments in additional water testing until FDA releases its guidance so you can be assured that the changes and investments you are making will be in compliance with the PSR.

Options if Your Water Does Not Meet Microbial Water Quality Criteria

Once the GM and STV values for the MWQP are calculated, they must be compared against the numeric criteria in the PSR (described in detail above). In order to be in compliance with the PSR, agricultural water used during growing activities has to meet both the GM criterion and the STV criterion.  If a calculated value is above one of those criteria, the PSR includes flexibility in the form of management options called corrective measures.  Growers have time, within the following year, to apply one or more of these corrective measures:

  • Manage the water use and produce handling to include a time interval for die-off or to allow for log reduction during other steps.  These management options result in calculated reductions to the original GM and STV value.  The reduction is based on expected rates of microbial die-off in the field or during storage, or log removal during processes such as commercial washing. 
  • Re-inspect the agricultural water system and take corrective action to address contamination sources or other issues. 
  • Treat the water, being sure that any antimicrobial pesticides (e.g., sanitizers, disinfectants) are used according to the label. 

Corrective measures will be covered in more detail in a future article – for now, hopefully, this is enough information to get you organized and headed in the right direction.   

There will be more written about water quality and water-related requirements in the PSR, and FDA is working on guidance to help guide compliance with the PSR. Contact the PSA if you have questions about what the water rules mean to you. For authoritative answers about PSR water quality requirements and regulatory compliance, you can submit questions to FDA’s technical assistance network.