Skip to main content

Produce Safety Special Feature: Getting to Know Vermont’s Agricultural Water

November 5, 2018

By Dominique Giroux, Vermont Agency of Agriculture, Food & Markets 

Water plays a huge role on produce farms. From field irrigation to post-harvest cleaning, water is an element that growers certainly cannot forgo. And while some farms are able to minimize their water use through rainfall and choosing not to wash produce, many rely on this natural bounty to sustain their crops and businesses. As the U.S. Food and Drug Administration (FDA) revisits the agricultural water requirements in the Food Safety Modernization Act (FSMA) Produce Safety Rule (PSR) the Vermont Produce Program at the Vermont Agency of Agriculture, Food & Markets (VAAFM) asked: “How well do we know our water?” The Vermont Produce Program dove deep into agricultural water this past summer to better understand the PSR’s current water requirements for water sampling, developed water sampling resources, and toured Vermont’s agricultural water sources with produce growers, University of Vermont Extension, and FDA.

Revisiting the PSR Agricultural Water Requirements

To provide context, let’s look back to February of 2018 when the Produce Safety Alliance Water Summit took place. The Summit centered on the Produce Safety Rule’s Subpart E – Agricultural Water and provided growers, Extension, university, state and other produce industry stakeholders a chance to voice agricultural water challenges, current practices, and research needs, and to provide collective feedback to the FDA on current requirements outlined in the PSR water standard. (Read more about the Summit at

Vermont Produce Program: Water Project

The primary Subpart E component that FDA is reconsidering are the number and frequency of water tests. FDA received feedback during, and after, the PSA Water Summit that indicated testing requirements are too burdensome and that further scientific background is needed to support how testing water can reduce microbial contamination of produce. Realizing that testing would not go away, even if the requirements are revised, the Vermont Produce Program applied for and received a USDA Specialty Crop Block Grant Program award to perform a Produce Farm Water Testing Pilot. This funding allowed the program to develop educational materials for produce growers on how to take an accurate water sample and prepare it for delivery or shipment to a qualified laboratory, and provided Vermont Produce Program staff with an increased understanding of the technical aspects behind agricultural water sampling to better assist growers. 

Developing Resources and Strengthening Technical Knowledge

The Agricultural Water Testing Labs in VT and Neighboring States factsheet was developed to determine the options available to growers seeking to understand the quality of their surface water (e.g. river, pond, lake) and ground water (e.g. dug well, drilled well). (View the factsheet at

The Produce Program took a series of water samples from the Connecticut, Winooski, and Lamoille Rivers and from Mill Brook in Williston. In addition, five tests were taken form a single sample point on the Connecticut River and delivered to five different labs. The outcome? The water sample results from each of the labs fell within a range of 20 – 34 MPN (most probable number) units of generic E. coli per 100 mL of water. The difference in MPN results could derive from a few variables: difference in water sample taken, hold time, and temperature. It took two scoops of water to fill the five sample bottles; it’s probable that the scoops consisted of different MPN because a river is, of course, a moving target. Next, the hold time – the time between sampling and processing – varied between the labs, which can have an impact on sample quality. Two of the sample bottles were processed within the same day, while the other three were processed the following day. Finally, temperature: it is recommended that a sample stay below 50°F, but not frozen, during transport. While measures were taken to chill samples, some had a longer hold time, resulting in varying temperatures.

As the Vermont Produce Program has been out visiting produce farms throughout the summer for onsite visits and On-Farm Readiness Reviews, it became apparent that while some growers are testing their water, there are those not familiar with taking a water sample. Thus, the team developed a video (view the video at outlining how to take a water sample with an accompanying factsheet, Water Sampling 101 (view the factsheet at Growers interested in getting to know the quality of irrigation or post-harvest agricultural water will find these resources as useful starting points. 

A strong conclusion that was drawn throughout this process was that while it is beneficial to sample agricultural water, it is understanding how to use that information and the associated risk factors of agricultural water on farms that will assist in reducing microbial contamination risk of produce. “For me, what I want to know is if I’m looking at a water test or I’m looking at certain conditions in the river, is this a time I should be concerned, or do I not really need to be concerned if my water quality profile is below a certain threshold,” says Andy Jones, Intervale Community Farm manager.

FDA Water Tour

As previously mentioned, the FDA is revisiting the requirements outlined in the PSR under Subpart E – Agricultural Water. While the PSA Water Summit provided beneficial feedback, the FDA Water Team conducted an on-farm Water Tour throughout the country’s regions to see first-hand the variances and practices related to agricultural water.

The Vermont Produce Program at VAAFM, University of Vermont Extension, New Hampshire Department of Agriculture, Markets and Food, and University of New Hampshire Extension hosted FDA on three New England produce farms to provide context of regional concerns and water practices. While it is uncertain as to how the FDA Water Team will apply the regional feedback, it is a positive that grower input and regional variations are being taken into consideration when the team revisits requirements in Subpart E.

What Should Produce Growers Do Now?

Growers are encouraged to continue sampling their agricultural water if they already do so, and if not, to consider taking a few samples throughout the growing season to get a better idea of their water sources. FDA, States, and Extension partners will continue working together to establish meaningful agricultural water requirements and resources growers need to implement risk reduction measures. In the meantime, water sampling is a proactive tool growers can use now to help identify baseline risks associated with their water. If you need assistance interpreting your sample results or determining whether your farm is subject to the FSMA Produce Safety Rule, connect with the Vermont Produce Program at or (802) 828-2433. To access produce safety resources, visit