Practical pointers around submitting water samples for food safety

Water sampling to meet federal on-farm food safety guidelines can be confusing. This article helps eliminate some confusion about taking and submitting a water sample.

Fresh produce growers looking to comply with either Good Agricultural Practices (GAPs) audits or the Food Safety Modernization Act (FSMA) usually have to take regular water tests. Since there are a number of different food safety requirements around water, and because none of them are the same, some practical pointers around water testing might be in order.

Current situation

Even if a lab conducts a water test you are looking to have done, it doesn’t mean they test every day of the week. Call ahead to the lab and ask questions well in advance of taking samples, like, “Do you process generic E. coli samples every day or on certain days?” Some labs may only run irrigation water samples two days a week. In those cases, any sample delivered to the sampling site after a pickup day might sit for several days before being tested, changing the contamination level in the water.

The Food and Drug Administration (FDA) has received feedback around the current FSMA agricultural water standard noting implementation may be too difficult given current realities. FDA has announced they are addressing this concern. Some key points they hope to solve include the hold time of samples to meet current analytical methods, not being able to find a lab that meets the current guideline and how to define separate water sources.

Current sampling to meet guidelines requires transporting the sample on ice to a lab within 6 hours. In some geographic areas, this may be impossible. The current approved water testing method specified under FSMA (Modified mTEC, method 1603) is not a readily available test in most of the United States. Some flexibility was granted in that the lab chosen to carry out the test did not need to be certified to carry out the test. Regardless, finding a lab to carry out this test has proven challenging.

Finally, the need for understanding where one water source ends and another begins is still unclear. In some water systems, a shared surface water source may have several points where water is drawn. The law is unclear under what circumstances one or another user of a shared water source would both have to test. These issues will be addressed in the new guidelines.

What you can do

Stepping back from these concerns about FSMA regulations, it is important to put water testing in context. If you are currently not testing any agricultural water used on fresh produce for generic E. coli, it is recommended you start. Choose any lab or method, as long as the result gives a number of generic E. coli that will help you understand the quality of your water supply.

If you are currently taking water samples for GAPs, use the accompanying guidance for the GAP scheme you are using to determine what to test for and how frequently. Don’t change anything about what you are testing for or how often you are testing. As the federal guidelines change, and the FSMA law gets better understood, then you may need to change testing methods and frequency of sampling. Until then, it is better to know what’s in your water using a test that hasn’t been formally approved than to continue to be in the dark about your water quality.

If you would like more information on water testing, feel free to contact the Michigan State University Extension Agrifood Safety Workgroup at 517-788-4292 or

Did you find this article useful?