Agricultural Water

Agricultural water can be divided into two groups: production water and postharvest water.

Production water: Any water that is used during growing activities. Production water use includes irrigation, fertigation, crop sprays, cooling, frost protection, and dust abatement.

Postharvest water: Any water that is used during and after harvest, including during packing and holding activities. Postharvest water use includes rinsing/washing, commodity movement, cooling, ice making, postharvest fungicide and wax, handwashing, cleaning and sanitizing.

Agricultural water from different water sources inherently carry different levels of risk.

Public water supply: Water from public water supplies has been treated and monitored by the public water utility and therefore has the lowest risk of being contaminated.

Ground water: Ground water, or well water, is generally less likely than surface water to be contaminated. The potential for well heads to be installed incorrectly and for contamination of ground water from septic tanks puts ground water at a slightly higher risk of contamination than a public water supply.

Surface water: Surface water, including rivers, streams, lakes, ponds, man-made reservoirs, and any other water source that is open to the environment, is the most risky agricultural water. Water quality from surface water can vary greatly between sites and over time. Some major contamination risks include wildlife, water runoff from upstream livestock operations, and wastewater discharge.

General Recommendations for Managing Production Water

  1. Test your water. It is important to know the microbial quality of your water, both at the water source and at the output. While public water is tested and treated accordingly by the public water utility, it is still important to test public water from your faucets/hoses/etc. For information on how to collect and where to send water samples, and what test to order, see relevant questions under the heading "General FSMA Water Requirements" below.
  2. Make a water distribution map. Map your water sources, permanent fixtures (wells, holding tanks, valves, etc) in your water distribution system, and the flow of the system. Include the following for each water source: the extent of your control, the degree of protection, the use of adjacent, nearby, and upstream land, the likelihood of contamination before water from each source reaches your farm. This allows you to identify risks in your water system and plan accordingly.
  3. Think about your water usage and make changes to lower your risk. Keep potentially risky water (usually surface water) from contacting the harvestable portion of any crop. In general, the less contact produce has with water, the lower risk it has of becoming contaminated. For example, this may mean switching from overhead irrigation to drip irrigation in some crops. See below for some relevant fact sheets.

General Recommendations for Postharvest Water

  1. Remember that all postharvest water, including water for produce washing and cooling, handwashing, ice-making, and cleaning and sanitizing of food contact surfaces needs to be done with potable water (water with no generic E. coli).
  2. Test your water if you use ground water as your postharvest water source, or obtain the testing certificate for municipal water. All water used post-harvest should be potable (with no generic E. coli) when it leaves the tap. Untreated surface water should not be used for any postharvest activities. For information on how to collect and where to send water samples, and what test to order, see relevant questions under the heading "General FSMA Water Requirements" below.
  3.  Think about your water usage and make changes to lower your risk. For produce washing, single-pass water (e.g. spray from a hose, conveyer, or barrel washer) is less risky than recirculated or batch water (e.g., from a recirculating conveyor or dunk tank). Recirculating water can become contaminated and present a cross-contamination risk, and must be maintained to be of adequate quality.
  4. Consider including a sanitizer in produce wash water. Sanitizers can help reduce the risk of cross-contamination in recirculated water and can help reduce the build-up of microbes and biofilms in single pass systems. Be aware, though, that sanitizers are pesticides (they kill microbes) and must be labeled for their intended use and handled and monitored carefully. The Produce Safety Alliance has compiled a list of sanitizers that are labeled for use on produce and food contact surfaces; see the resources and video tutorial below for more information.

Agricultural Water and FSMA

The following info addresses how to comply with the Agricultural Water section of the FSMA Produce Rule as of May 2, 2018. The FDA is currently reviewing this section of the rule in order to address questions about the practical implementation of this section and to consider how they might reduce the regulatory burden or increase flexibility of this section. Until more is known, the requirements described in this Q&A are the rule.

General FSMA Water Requirements

When do I need to begin testing my water?

The currently proposed Agricultural Water Rule has extended compliance dates for all provisions dealing with agricultural water beyond the originally published dates. To find out what farm size you fall into, use our FSMA Compliance Tool.

Business Size FSMA Compliance Date Water-Related Compliance Date
All other businesses (<$500K) 1/26/2018 1/26/2022
Small businesses (>$250-500K) 1/28/2019 1/26/2023
Very small businesses (>$25K-250K) 1/27/2020 1/26/2024
Source: https://producesafetyalliance.cornell.edu/sites/producesafetyalliance.cornell.edu/files/shared/Clarification%20of%20Compliance%20Dates%20-%20Resized.pdf

How do I collect water samples?

Some testing methods or labs require specific collection techniques – when you call your lab to ensure that they are certified to test your water, ask them for collection, storage, and handling instructions.

Regardless of specific lab instructions, all samples must be collected in sterile bottles. Make sure you don’t contaminate the bottle by touching the lid, mouth, or inside while collecting samples.

Do not rinse sterile bottles with tap water before sampling. Some bottles are lined with protective chemicals that should not be rinsed out, and residual chlorine in municipal water may kill bacteria in the sample.

When sampling from a distribution system (e.g. from the tap, a drip line, overhead irrigation system), let the water run to flush the system before sampling. This will ensure you collect a representative sample.

For any water source, you need to collect samples that are representative of the water that will be used during growing. For example, for ground water, one sampling location might be as close to the point of intake as possible. Water sampling is not required if you use public water supply, but it can be useful to test water from your taps, from the end of drip lines, or from overhead irrigation systems to determine if there is a point of contamination in your water distribution system.

Video from the Vermont Agency of Agriculture on how to collect a water sample.

What test do I order?

All of the acceptable tests detect generic E. coli. For both production water and postharvest water, you can use any of the methods in the table below. You will get quantitative results from these test (e.g. how much E. coli is in my water?)

Membrane filtration methods (colony forming units; CFU/100 mL)
Published method name Shorthand method name
EPA Method 1603 Modified mTEC agar
EPA Method 1103.1 mTEC agar
Standard Methods 9213 D
ASTM Method D5392-93
EPA Method 1604 MI agar
Standard Methods 9222B and 9222G m-Endo then NA-MUG agar
Hach Method 10029 m-ColiBlue 24 ampules
Most probable number methods
(MPN/100 mL)
Published method name Shorthand method name
IDEXX Colilert test kits, only if using Quantitray 2000 There are several Colilert method options. Be sure that the lab provides one of the approved methods.
IDEXX Colilert-18 test kits, only if using Quantitray 2000
Source: https://producesafetyalliance.cornell.edu/sites/producesafetyalliance.cornell.edu/files/shared/documents/Water-Analysis.pdf

For postharvest water only, you can also use any of the presence/absence tests listed below. These tests will only tell you whether or not there is any detectable amount of E . coli in your postharvest water but will not give you a quantity.

  • TECTATM EC/TC medium and the TECTATM Instrument
  • Modified ColitagTM
  • IDEXX Colilert Test Kit
  • IDEXX Colilert-18 Test Kit
  • IDEXX Colisure Test Kit 
  • E*Colite Bag or Vile Test
  • 101298 Readycult Coliforms 100

Where can I find this information as published by the FDA?

https://www.fda.gov/Food/FoodScienceResearch/LaboratoryMethods/ucm575251.htm

What lab can I send my water samples to for testing?

Click here for a map of labs in the Northeast that conduct testing approved by the FDA for FSMA compliance. Please note that lab certification status for specific methods changes frequently. Make sure you call ahead to any lab you’re planning on using to make sure they are still certified to use any given method, even if they’ve tested your samples in the past.

Samples generally must be delivered to a lab within 6 hours after collection. Keep this in mind when choosing a lab to bring your samples to.

Compiled May 2018 from the MA DEP Online Searchable Laboratory Certification Listing.

Be sure to ask your lab for instructions on the following things:

  • Type of sample container
  • How to take the sample
  • Acceptable hold times
  • Sample storage
  • Transportation expectations

What do my test results mean?

All of the methods listed above test for generic E. coli, which is an indicator of fecal contamination. Depending on the test, you will get results in the form of colony forming units (CFU)/100 mL or most probable number (MPN)/100 mL. Both of these values represent an estimate of the bacterial concentration in your water and can be used to calculate geometric mean and statistical threshold value (see “What is the acceptable threshold of E. coli levels in production water?”).

Sample water test result using EPA 1603

How much does it cost to test each water sample?

Prices vary between labs and methods, but usually, it costs between $15 and $50 per sample.

What records do I need to keep regarding agricultural water in order to comply with FSMA?

To comply with FSMA, you must keep the following records:

  1. Results from your water tests
  2. Results from your yearly inspection of all water distribution systems. See template below.
  3. If you treat your recirculated water, you must keep records. See “Water Treatment Monitoring Template” below. In addition to the information in this template, you may also want to monitor the amount of free sanitizer in your water as you use it and record that monitoring.
  4. Documentation of any corrective changes you make to your water sources or distribution systems to eliminate a source of contamination.
  5. If your production water is above the acceptable microbial threshold and you extend the time between water applications and harvest to account for microbial die-off, you must record:
  • The time interval you implemented
  • The die-off rate you used for calculations
  • The dates of relevant activities (the last water application and harvest)

Templates for required agricultural water recordkeeping:

Production Water and FSMA

How frequently do I need to test my production water?

Water Source Production Water Testing Requirement
Public water supply Copy of test results from public water utility or current certificates of compliance
Ground 4 times during the growing season for the first year. For each following year, 1 new sample is taken and the oldest test result is dropped.
Surface 20 times during the first 2-4 years. For each following year, 5 new samples are taken and 5 oldest are dropped.

Where do I find this information in the FSMA Produce Rule? §112.46(b)

What is the acceptable threshold of E. coli levels in production water?

The rule requires the following for generic E. coli levels in production water per 100 mL water sample:

  • 126 or less CFU per 100 mL water geometric mean (GM), and
  • 410 or less CFU per 100 mL water statistical threshold value (STV).

The geometric mean (GM) is calculated by averaging the number of CFUs from each of your samples.

The statistical threshold value (STV) measures the variability of generic E. coli levels in your water source. Setting an STV allows for your samples to have some spikes in E. coli levels over time, when surface water levels are low, for example, without your water being deemed unusable.

Many different tools exist for calculating GM and STV. See below for one example.

  • Surface Water (Western Center for Food Safety, Version 6.0, October 2, 2017)
  • Ground Water (Western Center for Food Safety, Version 5.0 October 2, 2017)

These CFU levels are the current recreational water standards (i.e. standards for lakes, rivers, beaches). The proposed agricultural water rule is based on recreational water standards because there is insufficient research regarding safe bacterial levels in agricultural water. The FDA is currently seeking out additional research in this field and has extended compliance dates for the Agricultural Water section of the rule beyond the original dates for this reason. Until we have more information, however, the CFU thresholds listed above stand as the rule.

Where do I find this information in the FSMA Produce Rule? § 112.44(b)

What do I do if my production water is above the acceptable threshold for generic E. coli?

If your production water has E. coli levels above 126 CFU/100 mL (GM) or above 410 CFU/100 mL (STV), you must stop using water from that source as soon as is practicable or within 1 year at most, unless you do one of the following:

  1. Determine why your water is contaminated and fix it. This is the best course of action. Re-inspect your water distribution system to determine the source of contamination, make changes to eliminate the source of contamination, and then re-test your water to ensure that you successfully lowered the level of E. coli in your water to acceptable levels. Keep records of what went wrong, how you fixed it, and your before and after water test results.
  2. Change your irrigation method so that the water does not contact the harvestable portion of the crop. For example, with fruiting crops for which the harvestable fruit does not touch the ground, switching from overhead to drip irrigation will prevent the contaminated water from ever contacting the fruit. For root crops, this is not an option.
  3. Apply a time interval between the last water application and harvest. Microbes living on produce in a field are exposed to UV light and will become desiccated, both of which will kill them. Using the rate at which microbes die off, one can hypothetically calculate the amount of bacteria that will remain on produce given the initial number of CFU in the water and the amount of time that passes. While this is given in FSMA as an option for mitigating contaminated production water, there is conflicting science behind this technique and we do not recommend relying on die-off rates. If you decide to use this technique, please see further explanation below.

    To calculate the extent of microbial die-off after applying contaminated water, use the die-off rate of 0.5 log per day, for up to four consecutive days. The Western Center for Food Safety has developed tools for determining how many days are necessary for microbial die-off:
    • Surface Water (Western Center for Food Safety, Version 6.0, October 2, 2017)
    • Ground Water (Western Center for Food Safety, Version 5.0 October 2, 2017)
    • If you use this method, you must keep records of the following (see template below):
  4. Treat your water by putting a sanitizer in line with your irrigation water. One sanitizer labeled for use in irrigation water is SaniDate (5.0 or 12.0). Keep records of any water treatment you do.

Where do I find this information in the FSMA Produce Rule?

  • What to do if your water has more E. coli than is acceptable: §112.45(b)
  • Water treatment requirements: §112.43

What else does FSMA require me to do regarding production water?

  1. Inspect your water sources. At the beginning of a growing season, as appropriate but at least once annually, growers must inspect all of a farm’s agricultural water systems, to the extent they are under the farm’s control, to identify produce safety hazards. Use the template below to record the following:
    • What type of water is each water source – ground, surface, or municipal water?
    • The extent of your control over each water source
    • The degree of protection from the environment of each source
    • The use of adjacent and nearby land
    • The likelihood of contamination by another user of the water before it reaches your farm

      Water System Inspection Template
  2. Maintain all water sources and distribution systems, to the extent that they are under your control, to prevent them from becoming sources of contamination. This includes:
    • General well/tank/treatment equipment maintenance (repairing and replacing parts as needed)
    • Keeping water sources free of debris, trash, domesticated animals, and any other potential sources of contamination
  3. Prevent produce from coming into contact with pooled water in the field. This may involve using protective barriers, staking plants, or simply not harvesting produce that you’ve observed contacting pooled water in the field.

Where do I find this information in the FSMA Produce Rule? §112.42(a)

Postharvest Water and FSMA

How frequently do I need to test my postharvest water?

Water Source Production Water Testing Requirement
Public water supply Copy of test results from public water utility or current certificates of compliance
Ground 4 times during the growing season for the first year. For each following year, 1 new sample is taken and the oldest test result is dropped.
Surface Not acceptable for use as postharvest water

Where do I find this information in the FSMA Produce Rule? §112.46(c)

What is the acceptable threshold of E. coli levels in postharvest water?

The rule requires the following for generic E. coli levels in postharvest per 100 mL water sample:

  • Single-pass postharvest water: 0 CFU/100 mL
  • Recirculated and batch water: Begin with 0 CFU/100 mL

These standards are the standards acceptable for drinking water.

Where do I find this information in the FSMA Produce Rule? §112.44(a)

What do I do if my postharvest water is above the acceptable threshold for generic E. coli?

If you detect any E. coli in your postharvest water (either in single-pass water or recirculated water), you must immediately stop using that water. You cannot use that water for postharvest activities (including hand-washing, ice-making, produce washing or cooling, and cleaning or sanitizing of any food contact surfaces) until you determine the source of contamination and eliminate it. Once the source of contamination is gone, sanitize your water distribution system, and then re-test your water to ensure that you successfully lowered the level of E. coli in your water to acceptable levels. Keep records of what you did to fix the problem and of any sanitizers that you used to clean the system.

Where is this information in the FSMA Produce Rule? §112.45(a)

How should I manage recirculated water?

Recirculated, or batch water is water that will be reused over multiple batches of produce. To comply with FSMA, recirculated water must begin with no detectable E. coli. As batch water recirculates, microbes from produce will accumulate in the water. However, FSMA does not provide guidance on microbial content thresholds that recirculated water must meet as it is being used. FMSA only requires that recirculated water remains safe and of adequate sanitary quality throughout its use.

The specific requirements regarding recirculated water in FSMA are as follows. You must:

  1. Establish and follow water-change schedules. Your water-change schedule can be based on any factor(s) you deem appropriate for your operation, as long as you can justify it. You can decide to change your wash after a certain number of produce batches have been dunked, after you’re done washing one crop, after the water reaches a certain temperature, etc. Whatever factor(s) you base your water-change schedule on, write up a Standard Operating Procedure (SOP), post it in a visible place in your washroom, and make sure all relevant employees follow the procedure.
  2. Visually monitor the turbidity of the water. Turbidity is a measure of the cloudiness of water and is easy to observe visually. Wash water becomes turbid due to the buildup of soil and organic matter from produce. Organic matter binds to and deactivates chlorine in sanitizers. However, turbidity does not necessarily correspond to bacterial content levels in water; water can contain high levels of bacteria and have very low turbidity, or look very clear. Nonetheless, FSMA requires that you monitor the turbidity of your recirculated water and take the level of turbidity into account when developing your water-change schedule.
  3. If you treat your recirculated water, you must keep records of that treatment.
  4. Minimize the potential for infiltration by monitoring and maintaining appropriate water temperatures. See this fact sheet on Infiltration for more information.

Managing recirculated water remains a vague area both in general and within FSMA. As things stand now, in order to comply with FSMA and to produce food as safely as possible, we recommend doing the following:

  • Create Standard Operating Procedures (SOPs) for water-change and water temperature schedules, and to outline your approach to avoiding infiltration, and post them in an accessible area, and make sure everyone on your farm follows set procedures.
  • Keep records of your water temperature monitoring and any treatment of recirculated water with sanitizers.

Water Treatment Monitoring Template

Other Relevant Fact Sheets:

Where do I find this information in the FSMA Produce Rule? §112.48

Where can I dump waste water?

Agricultural waste water disposal is not regulated in FSMA but may be regulated by other agencies in your town or state. Contact MDAR, your local FSMA inspector or technical service provider to ask about how different regulations will interact in your area on this topic.

In general, agricultural waste water (including from hand-washing stations and produce wash stations) should be discharged in a way that prevents entry of water and accompanying sediment and microbes into ground water or surface water. Waste water should also be discharged in a way that prevents it from contaminating harvested or harvestable produce. This means discharging across grassy or sodded areas with deep soil (or no shallow bedrock or ground water) that are large enough to absorb all of your discharge water. For specific guidance on how to design a waste water discharge system, please see this fact sheet from UVM: Guidance on Wash Water Discharge from Vegetable Pack Sheds – Advice on System Design. Remember that the water quality regulations mentioned in the beginning of the UVM fact sheet are specific to Vermont.

If you treat your postharvest water with a sanitizer, you must follow any label instructions for discharge and disposal, as you would with any other pesticide. Some sanitizers do not have specific disposal instructions, and they can be discharged along with untreated waste water.