Agricultural water is used for irrigation, application of pesticides or fertilizers, produce washing and the washing and sanitization of harvest and post-harvest equipment, tools, surfaces and vehicles. Because water can be the source of, and facilitate the spread of bacteria and other pathogens, production of safe produce is dependent on safe agricultural water sources and good management of your water system.
Definition of Agricultural Water
Agricultural water is water used in covered activities on covered produce where water is intended to, or is likely to, contact covered produce or food contact surfaces, including water used in growing activities (including irrigation water applied using direct water application methods, water used for preparing crop sprays, and water used for growing sprouts) and in harvesting, packing, and holding activities (including water used for washing or cooling harvested produce and water used for preventing dehydration of covered produce).
The Rule requires that all agricultural water be safe and of adequate sanitary quality for its intended use. There are different standards of safety for different uses, whether referring to pre-harvest uses or post-harvest.
The Produce Safety Rule agricultural water rules are found in Subpart E (page 74554 of the Federal Register or page 202 of the Rule). Review the summary of this section of the Rule.
While the agricultural water rules are part of the original Produce Safety Rule, subsequent concerns about the scope and complexity of agricultural water rules resulted in the development of an updated agricultural water rule, Standards for the Growing, Harvesting, Packing, and Holding of Produce for Human Consumption Relating to Agricultural Water. The new Rule does not significantly change the requirements of harvest and post-harvest water, but there are significant changes to the pre-harvest water rules.
Harvest and Post-Harvest Water
Farms should continue to follow the rules found in the 2015 Produce Safety Final Rule (80 FR 74461), Subpart E (Agricultural Water). Managing post-harvest agricultural water
Post-harvest water that meets Rule requirements can be from municipal water sources or from a tested well or treated surface water source that meets the standard of no detectable generic E. coli. This is not the same as potability – the standard for drinking water or water used for sanitation in a home, institution or restaurant. If your well water has been tested for potability, however, it will meet the standards for agricultural water under the Rule. You may use presence/absence tests for this post-harvest water because generic E. coli must be absent or 0. Management of post-harvest water includes inspection of the system, testing, and managing produce wash water to minimize contamination of produce.
Harvest and Post-Harvest water system inspection: Identifying the Risks
The first tool (and a requirement of the Rule) for the farmer is a thorough agricultural water system inspection. This inspection must be done at least yearly and more often if there are any questions that the integrity of the system has been compromised in any way during the season, or, if there is a change to the system such as installation of new well or water treatment system.
Start with listing all of your harvest and post-harvest water sources: each well and municipal water source.
- It is helpful to draw a map of your farm or you can download a GPS map of your farm from your computer. Then note on the map where the sources of water used in harvest or post-harvest are--especially in relation to fields and to sewage systems, animal operations, port-a-potties, or other potential sources of contamination.
- Inspect piping and pumping systems from wells and/or municipal systems. Check the integrity of well heads and covers.
- Inspect (or have a plumber inspect) back flow prevention devices that ensure the protection of water sources such as wells or municipal systems, especially when these sources are used in toilet systems, pesticide or chemical fertilizer application systems, packing house wash or sanitation systems, etc.
- Conduct any water testing as required by the Rule, a third party auditor and/or a customer. Even if you are exempted from the Rule, a water system inspection and regular testing makes good business sense.
If any deficiencies are found, implement needed corrective actions so that the safety of your agricultural water is not compromised and risks are minimized or eliminated.
Testing:
Again, water used in post-harvest applications must meet the standard of no detectable generic E. coli. Conduct testing at least once yearly prior to normal use in a post-harvest operation. Keep all water test records on file.
Water treatment: washing produce
If you choose to wash produce (not required by the Rule), it is important to understand that while washing is employed to clean produce of dirt and debris, it can also contribute to contamination of produce if the water is not kept clean. If one apple or one head of lettuce is contaminated and the water is not kept clean, uncontaminated product in the wash bin can become contaminated. Water is a great carrier of bacteria from a dirty/contaminated product to a clean one. The risks associated with post-harvest water depend in part on the type of wash water system you are using.
Single pass water is water used in a bunch or root washer, or a flume. The water is constantly replaced with fresh water (water is not recycled and reused for subsequent batches). It may still make sense to use a sanitizer in single pass water systems in order to keep equipment cleaner and prevent the buildup of biofilms, a sticky substance that can provide a place for bacteria to live and multiply.
Recirculating or batch water is either recycled in your water system or it is in a dump tank or other type of tank and several batches of product are washed before the water is changed. Again, sanitizer is a good idea because, especially if produce is dirty, sanitizer can help minimize cross contamination. Sanitizers will also help to keep equipment clean.
Keeping water clean
There are two ways to minimize cross contamination by wash water: monitoring turbidity and using sanitizers.
Turbidity
Turbidity is the measure of cloudiness of your water. When dirt, soil, and plant debris (leaves, etc.) build up in the water, it becomes dirtier and cloudier. The dirty water potentially results in pathogen contamination of your product. Visual cues can tell you if the water is too dirty or is too turbid to continue using it. You can also use a turbidity meter or a Secchi disk, which sits on the bottom of the water tank. When the disk is no longer visible through the water, then it is time to change the water.
Water change schedules should be determined for different products and the variety of conditions (rainy weather leading to more mud and dirt on product). Use your experience or keep records of future wash water change schedules. Then, develop an SOP so that workers will have a standard procedure to follow when washing produce. This document has more information on measuring turbidity.
Sanitizers
Sanitizers, while not required by the Rule, will help to minimize both cross-contamination (dirty product to clean product) and to minimize build-up of bacteria and biofilms in wash tubs, flumes, and root washers. The sanitizer in the wash water is there to keep the water and equipment clean—not to clean or sanitize the product itself.
If you choose to use a sanitizer, then you must follow rules for use of sanitizers and keep records of how, when, and what you are using.
All sanitizers must be EPA (US Environmental Protection Agency) approved and labeled. All label instructions for use must be followed. Safety Data Sheets (SDS) must be kept on file.
The Produce Safety Alliance has a list of approved sanitizers that can be used in produce water applications (irrigation, washing, and equipment sanitation).
- Labeled Sanitizers for Produce information and Excel Tool updated 1/2024
Water temperature
Water temperature can have on impact on the safety of produce that is being water cooled or washed. Some produce is at greater risk for infiltration. Infiltration happens when produce is warmer (i.e. field warm) than the water that is being used for cooling/washing. Bacteria and other microorganisms that may be in the water (due to an apple contaminated with bird droppings, for example, or a melon that was growing on soil contaminated with feces from wildlife), can infiltrate or seep into the fruit or vegetable as the warm produce cools down and potentially “sucks in” contaminated water, through the stem end.
This is most likely to happen if produce is allowed to sit in/soak in water for a longer period of time and if the produce is bruised or the skin is broken. Certain varieties of produce are also more prone to infiltration through the stem end, including, but not limited to, tomatoes, melon, and apples. It is important that you know the characteristics of your product and know if it is likely to be prone to infiltration.
You can minimize the effects of infiltration by using a sanitizer in the water. And, in addition, by ensuring that the water temperature is no more than 10 degrees colder than the produce you are washing. Sometimes it might be necessary to add warmer water to achieve that standard. It is also a good idea to take the temperature of the wash water if you think this could be a problem to make sure that your wash water is not too cold.
Another reason to monitor water temperature is to ensure that your sanitizer is effective. If water temperature is too high and you are using a chlorine sanitizer, it can actually cause the chlorine to evaporate and reduce the concentration and effectiveness of the sanitizer. Be sure to read all label instructions for your sanitizer to see if it is necessary to monitor the temperature of your wash water.
An inexpensive standard bimetallic dial type thermometer (often seen in restaurants or chef’s pockets) can be used for this. Be sure to immerse the stem at least up to the notch on the stem. These thermometers are easy to calibrate in ice water and should be recalibrated often. A digital or instant read thermometer can be more accurate and quicker to use, though they may be a bit more expensive. Follow manufacturer’s instruction regarding calibration. Be sure to keep a record of temperatures taken.
pH
Depending on the type of sanitizer you are using, the pH of your water may impact the effectiveness and the safety of the sanitizer. If the water is too alkaline (high pH), it may reduce the effectiveness of the sanitizer: if the pH is too low (too acidic), it may cause development of a toxic gas if you are using chlorine based sanitizer. It is important to know the characteristics of your sanitizer so you know if the pH of your water is a concern.
If you need to test and monitor your water pH, you can use either pH test strips or a pH meter. Test strips are an inexpensive alternative, but may not be as accurate. Be sure to purchase test strips that are testing for the pH range your sanitizer needs to be effective. Also, replace test strips yearly as they can become less accurate over time. Talk to your ag chemical/foodservice chemical representative if you have questions about the product you are using.
If you choose to purchase a pH meter, keep in mind that you will also need to purchase chemicals called buffers that are used to calibrate a pH meter. For more information on the purchase and use of a pH meter, contact your produce safety Extension Specialist.
Pre-harvest Agricultural Water
Take a look at the Final Rule, linked here: Standards for the Growing, Harvesting, Packing, and Holding of Produce for Human Consumption Relating to Agricultural Water (Pre-Harvest Agricultural Water Rule, 2024)
The rule establishes compliance dates for the pre-harvest agricultural water provisions for covered produce (other than sprouts) as follows:
| Large farms | 9 months after effective date | April 7, 2025 |
| Small farms | 1 year, 9 months after effective date | April 6, 2026 |
| Very small farms | 2 years, 9 months after effective date | April 5, 2027 |
The effective date is July 5, 2024
FDA amended the produce safety regulation to address concerns about the practical challenges of using the ag water microbial water quality criteria and testing requirements that were in the original Rule and have been part of the PSA Produce Safety training curriculum since the beginning.
In the new Rule, there is a requirement for pre-harvest agricultural water assessments that covered farms will use to identify what measures they need to take to ensure that the water they use is of safe and adequate sanitary quality.
Corrective measures or mitigation measures (in case risks are identified during the assessment) will be used to address the known or reasonably likely hazards in ag water systems.
FDA Final Rule on Pre-Harvest Agricultural Water fact sheet
Here is a review of specific changes to Subpart E
Covered farms will conduct an annual Ag Water Assessment
When conducting the Ag Water Assessment (AgWA), farmers must review and assess the entire water system.
- What are the sources, what is the nature of the source, where is the source located? As we know different sources have different levels of risk associated with them on a continuum from surface sources (highest risk and variability due to environment, climate, animal and land use influences) to well water and public water sources (which are the least risky).
- What kind of distribution system are you using? Are there risks associated with that? When assessing, review the type of application method you are using—overhead, drip or other methods (some parts of the country use flood irrigation or furrow irrigation). You may be using a drip system, but what happens if there is a leak? Closed piping systems do have risks—do you have adequate backflow prevention devices?
- What are possible sources of contamination – both adjacent (sharing a border) and nearby animal facilities or manure storage facilities? Runoff or air drift from these facilities? Wildlife? Other users of the water source? What can you do to protect your source? What do you have control over? What do you NOT have control over and what can you do about it?e entire system must be considered during an assessment.
- Think about your crops. You need to know and understand the food safety concerns and risks of each crop you grow. Do your research. Are the surface characteristics an issue (rough vs smooth)? Is your crop susceptible to internalization during production (due to the nature of the crop—there is some research (though nothing definitive) regarding the uptake of pathogens in leafy green crops. If your crop is damaged by a weather event, such as hail, that could be a place where bacteria can gain entry.
- Where is the edible portion of your crop –close to the ground, in the ground, in the air? And how does that potentially impact in-field contamination (concerns for splash on lettuce leaves or use of drip on root crops that can be eaten raw).
- Consider the time interval between the last time ag water is applied and the harvest date.
- Climate can have a variety of effects on the survival, transmission, and growth. For example: Some pathogens (Salmonella and E. coli) are more likely to decrease with increasing temperatures. --the same is true of their survival in water. Airborne transmission of pathogens is likely to increase with windy/dry conditions. And, heavy rain events have been associated with increased populations of pathogens. The point here is to know your surroundings and be aware of weather changes that may increase or decrease the risk that pathogens may be spread, survive or result in the decrease in pathogen populations. Obviously, we cannot predict weather, but being aware of trends and day to day changes can help you to assess the risks to the safety of your water sources.
If farmers determine, as a result of reviewing their assessment outcomes, that the ag water is not safe or not of adequate sanitary quality for the intended use, then they must Immediately discontinue use AND take corrective measures before use at pre-harvest.
FDA Agricultural Water Assessment (AgWA) fact sheet
According to the FDA…
- If there is one or more known or reasonably foreseeable hazards related to animal activity, BSAAOs, or untreated or improperly treated human waste for which mitigation is reasonably necessary, you must implement mitigation measures promptly, and no later than the same growing season.
- If there is one or more known or reasonably foreseeable hazards not related to animal activity, BSAAOs, or untreated or improperly treated human waste, for which mitigation is reasonably necessary, you must implement mitigation measures as soon as practicable and no later than the following year OR test water as part of the assessment and implement measures, as needed, based on the outcome of the assessment.
- If it is determined that there are no known or reasonably foreseeable hazards for which mitigation is reasonably necessary, continue to inspect and adequately maintain the water system(s) regularly, and at least once each year.
If there are any conditions that might indicate changes in the season that adversely affect ag water safety (i.e. major flooding involving a river used as a water source), then a subsequent assessment should be carried out. Otherwise, assessments are conducted annually.
Exemptions from the Ag Water Assessment requirement:
If a farm is using water that is from a municipal water source (must provide annual water test results from water company); is treating their water in a way that adheres to the Produce Safety Rule requirements; or if the water meets the requirements that apply to harvest and post-harvest ag water (i.e. tested well water), then the farm does not need to conduct an Ag Water Assessment.
Records to keep
You must document your AgWA with a written record. In this record, describe what you include in your assessment, the outcomes of your assessment and how you evaluated the outcomes to determine if there were any risks associated with your ag water and how you plant to correct/mitigate those risks. If testing is done, must include sampling and testing procedures and results in AgWA records.
Managing production agricultural water
Production water would include any water used directly on edible portions of the produce you are growing. Water used for direct irrigation methods (overhead, drip for covered products that grow underground [carrots, onions, garlic and others that can be eaten raw]; and water used for fertigation or pesticide application directly on edible product. This water can be sourced from rivers, streams or other surface water; wells; or municipal systems. Each source varies in risk and required testing frequencies.
Identifying the Risks: production ag water
While the Rule requires an AgWA (unless a farm meets exemption criteria), that assessment does not take the place of an annual water system inspection. The agricultural water system inspection must be done at least yearly and more often if there are any questions that the integrity of the system has been compromised in any way during the season.
- Start with listing all of your water sources: surface water (rivers, streams, ponds, cisterns); well water; and municipal water sources. If you truck in water, be sure to include that as well.
- It is helpful to draw a map of your farm or you can download a GPS map of your farm from your computer. Then note on the map where all of the water sources are –especially in relation to fields and to sewage systems, animal operations, port-a-potties, or other potential sources of contamination.
- Inspect piping and pumping systems from all water sources, including surface, well or municipal systems. Check the integrity of well heads and covers.
- Inspect (or have a plumber inspect) back flow prevention devices that ensure the protection of water sources such as wells or municipal systems, especially when these sources are used in toilet systems, pesticide or chemical fertigation application systems, packing house wash or sanitation systems, etc.
Water testing
Under the new Rule for production and pre-harvest water, testing is not required. However, you can conduct ag water testing as part of your water assessment or to help determine if mitigation measures are effective. The Rule does not identify testing frequencies, though you can find testing methodologies here: FAMA Final Rule Equivalent Testing Methodology for Agricultural Water Produce safety Rule
What the Rule requires: Agricultural water
- Conduct and document an annual water system inspection
- Conduct and document an annual water assessment
- Conduct and document any corrective actions or mitigation measures if water assessment indicates they are needed
- Monitor and maintain quality of post-harvest water used to wash produce (temperature, pH, sanitizer concentration, turbidity): monitor and keep records
What to do in addition to the Rule
Develop written SOPs for water system inspection, ag water assessment, and monitoring and maintaining quality of post-harvest water used to wash produce
Sample SOPs for agricultural water
SOP for using Peroxyacetic Acid (PAA) in wash water (Haddad, Cornell)
Handling Turbidity in Post-Harvest Wash Water (Michigan State)
Sample record keeping forms for agricultural water
Water System Inspection Record template
Water Treatment Monitoring Record
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