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Agricultural Production Water

What is agricultural water?

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)). The language directly from the Produce Safety Rule requires that “all agricultural water must be safe and of adequate sanitary quality for its intended use” (§ 112.41).

Although the Agricultural Water Standard under FSMA’s Produce Safety Rule is currently under revision, there are tools that produce growers and technical assistance providers can use to understand the general quality of a water source (surface, well or municipal) that is applied to fruit and vegetable crops during their production (or growing activities). These include developing a general understanding of water testing (how to test from different sources) and where to obtain a water test. The subsequent sections cover water testing and management under FSMA for agricultural water intended to or likely to contact covered produce (other than sprouts) during growing activities.

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Information on Testing Locations

The Produce Safety Rule and Agricultural Water

Note: At this time, the water standard for the Produce Safety Rule (PSR) is under review by the FDA, meaning that FDA does not intend to enforce the agricultural water provisions in subpart E of the produce safety regulation for covered produce, except for sprouts.  Farms may choose to continue with their current water testing programs or wait to establish a water testing program since FDA has proposed extending the agricultural water compliance dates under the PSR. This information is being provided to help growers understand the water quality standards that are in the current rule, with the understanding that there will be changes and more information provided from FDA in the future. 

FDA’s initial proposed water standard under the PSR state that growers should: 1) initially establish a Microbial Water Quality Profile (MWQP) for each untreated agricultural water source used during growing activities of covered produce (other than sprouts) using a direct water application method; and 2) conduct annual surveys for that water source in subsequent years. The water quality profile is based on the levels of generic E. coli detected in agricultural water via sampling. Please note that there are different requirements for agricultural water that comes from surface and ground (well) sources.

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(Produce Safety Alliance fact sheet)

The numerical evaluation criteria for calculating the MWQP of water intended to or likely to contact covered produce (other than sprouts) during growing activities are:

a. Geometric Mean (GM) of 126 or less CFU of generic E. coli per 100 mL water AND

b. Statistical Threshold Value (STV) of 410 or less CFU of generic E. coli per 100 mL water.

The tools below compare a grower’s MWQP to the microbial water quality criteria established under the Produce Safety Rule.

Several tools make it easier to calculate the GM and STV and to determine if agricultural water meets the criteria for appropriate application to produce before harvest. These tools were also designed to assist with making water management decisions if the water does not meet the criteria in the Produce Safety Rule.

For Untreated Surface Water:

  • Surface Water MWQP Calculator: Enter water sample results from surface water test to calculate the GM and STV for each test site (Western Center for Food Safety, Version 6.0, will download as Excel Spreadsheet).
  • Ag Water App: Assess the quality of multiple water sources, determine microbial water quality profile, and get real-time irrigation advice based on current water sampling conditions. Download onto any Wi-Fi enabled mobile device (Android, Apple, cell-phone, tablet, laptop) by visiting the Google Play or Apple app store. Type “Ag Water” in the search box and click download (University of Arizona).
  • Online Calculator: Determine the MWQP of a water source, using the online version of the Ag Water App, accessible from any device connected to the internet. Data entered cannot be saved in this calculator, but can be printed for record keeping (University of Arizona).

For Untreated Ground Water:

Initially FDA allowed only one water testing method, Method 1603 (a membrane filtration technique), to be used in developing MWQPs. Subsequently, FDA authorized additional water testing methods as acceptable under FSMA for Produce Safety Rule compliance, FDA’s Equivalent Testing Methodologies for Agricultural Water. The Produce Safety Alliance published this fact sheet on water testing and analysis under the Produce Safety Rule.

The source and delivery system for agricultural water is a potential risk area that farmers should plan to evaluate at the beginning of the growing season or any time when contamination is suspected. Not only is an annual inspection of the water supply system a Good Agricultural Practice, it is also a requirement under the Produce Safety Rule that will likely not change with the new standards. Western Institute for Food Safety and Security resources for water system inspection:

  • How to inspect your water system (video)
  • Record your evaluation of your water system (inspection form)

The Produce Safety Rule allows growers to treat agricultural water with EPA and FDA-approved chemical sanitizers as long as products are labeled for crop contact and used according to label directions. In addition, growers may also use other treatments such as ozone or UV irradiation, they have scientific evidence proving the treatment’s effectiveness. The resources below provide an overview of irrigation water treatment, as well as accurate testing of chlorine levels in irrigation water.

  • Explore four treatment methods for cleaning irrigation water for fruits and vegetables and practice testing water with the Test Strip Lab.
  • Learn how to accurately test chlorine levels in irrigation water and how to avoid common pitfalls of chlorine testing systems.

Additional Resources on Agricultural Water:

  • Watch the Produce Safety Alliance’s Water Summit (held on February 27-28, 2018) and look through resource materials.
  • Safe uses of agricultural water (Penn State, fact sheet).
  • Inspecting your water system (Michigan State, video).
  • Backflow prevention (CSU, fact sheet).