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.
General Information on Water Sampling and Testing:
- Assuring Water Quality (webinar)
- Water Testing 101 (fact sheet)
- Selecting an Analytical Laboratory (guidance document)
Information on Testing Locations:
- Soil, Water and Plant Testing Laboratory at Colorado State University
- Veterinary Diagnostic Testing Labs
- CO Department of Public Health and Environment Microbiological Testing
- Labs in Colorado conducting FDA-approved water tests:
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 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.
1. Steps to Developing a MWQP (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.
2. Tools to Calculate Geometric Mean (GM) and Statistical Threshold Value (STV)
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:
- Ground Water MWQP Calculator: Enter water sample results from ground water test to calculate the GM and STV for each test site (Western Center for Food Safety, Version 5.0, will download as Excel Spreadsheet).
- Ag Water App: (see above)
- Online Calculator: (see above)
3. Water Testing Methods
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.
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).