EAST LANSING, Mich. — The Produce Safety Rule (PSR) is one of seven rules in the Food Safety Modernization Act (FSMA) coming into effect in the next three years. Growers will be calling labs for water testing, and they will be using new FSMA vocabulary that lab techs and support staff may not have heard before. They must establish a Microbial Water Quality Profile for each of their water sources. The source and use of that water dictates the type and frequency of water test they need performed. The two water types under FSMA are Production Water, and Postharvest Water.
Here is a 1-page printable lab resource for staffers to post near their phones, “Lab resource: Food Safety Modernization Act (FSMA) water testing expectations for farmers who grow produce that is commonly eaten raw.”
Production water
What is it?
Production Water is any water that contacts the harvestable portion of produce during its growth. This includes irrigation, crop protection sprays, frost protection and more.
What sources are there?
Growers use three primary water sources for Production Water, depending on their location. Municipal water sources come from township, city or county water treatment or filtration plants. This water is piped to the farm as a utility service. Groundwater sources come from wells drilled on the farm. Surface water sources are from spring pools, sinkholes, ponds, lakes, rivers, streams, open-air cisterns, reservoirs, etc.
How often do they need to test each water source?
Growers that use municipal water sources for Production Water just need copies of their municipality’s testing records. Growers that use groundwater sources need 4 enumerative tests in the first year, followed by 1 sample per year after to create a rolling 4-year data set of at least 4 samples. Growers that use surface water sources need 20 enumerative tests in the first 2-4 years, followed by 5 samples per year after to create a rolling 4-year data set of at least 20 samples. Every ground and surface water source on the farm that is used as Production Water must be tested, and regardless of filter systems.
What tests are allowed?
The FSMA PSR currently allows nine enumerative tests. Growers are required to deliver samples to labs within 6 hours of collection. The allowed tests are:
- Method 1103.1
- Method 1603
- Method 1604
- Method D 5392-93
- Method 9213 D
- Method 9222 B
- Method 9223 B 24-hour with Quanti-tray 2000
- Method 9223 B 18-hour with Quanti-tray 2000
- Hach Method 10029
What are growers doing with the test results?
Growers are required to maintain a Geometric Mean (GM) and Standard Threshold Value (STV) using the results from the water tests. They must maintain a GM of ≤ 126 CFU or MPN per 100 mL of water and a STV of ≤ 410 CFU or MPN per 100 mL of water. These calculations may be something that an entrepreneurial lab can assist with. There are some pre-made tools available, including the Arizona Ag Water Calculator.
If their water data exceeds either of those thresholds they are allowed to use three Corrective Actions. 1) They can delay harvest after their last use of Production Water on the harvestable portion of the crop for up to four days, accounting for a 0.5 log reduction in bacterial loads per day (see printable lab resource). 2). They can re-inspect the Production Water source and distribution system, fix any problems, document and confirm that the fix was effective with another test. 3). They can treat Production Water with a sanitizer labeled for use on fruits and vegetables or food contact surfaces as applicable.
Postharvest water
What is it?
Postharvest Water is any water that contacts the harvested portion of produce after it is harvested. This includes water used for washing, flume transportation, ice, hydro-cooling, wax/fungicide sprays, etc.
What sources are there?
For Postharvest Water, growers are allowed to use any of the aforementioned water sources except untreated surface water.
How often do they need to test each water source?
Growers that use municipal water sources for Postharvest Water just need copies of their municipality’s testing records. Growers that use groundwater sources need 4 tests in the first year, followed by 1 test per year after.
What tests are allowed?
At this point, any one of the aforementioned enumerative E. coli test are allowed.
What are growers doing with the test results?
Growers must maintain no detectable E. coli in their Postharvest Water. If water tests detect any E. coli in 100 mL of water, growers can use two Corrective Actions:
1) They can re-inspect the Postharvest Water source and distribution system, fix any problems, document and confirm that the fix was effective with another test.
2) They can treat Postharvest Water with a sanitizer labeled for use on fruits and vegetables or food contact surfaces as applicable.
Are Michigan labs ready?
To aid growers in finding a local lab, Michigan State University Extension is creating a Google Map (https://tinyurl.com/MIagwaterlabmap) that highlights labs that offer the tests allowed by the PSR rule. If your lab offers one of the above tests and you want the lab to be included on this map for Michigan growers, please fill out this form(https://tinyurl.com/MIagwaterlabsurvey) to help growers find you.
For more information on on-farm food safety, as well as updates on the PSR, visit the MSU Extension Agrifood Safety Webpage.
— Ben Phillips, Michigan State University Extension
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