FSMA – Water

FSMA Agricultural Water Information

FSMA defines agricultural water used on produce farms into two main categories: 1) water used during growing of crops (growing/production activities) and 2) water used during harvest, postharvest, and hand washing.

FSMA Requires You Complete the Following Agricultural Water Items:

  1. At least annually, you must inspect your farm’s entire irrigation system to monitor for any problems.
  2. To the extent that they are under your control, you must adequately maintain all water sources on your farm.
  3. Test each of your water sources to verify that you’re using water with acceptable generic E. coli levels.
      • Water used during harvest, postharvest activities, hand washing, and growing sprouts must test results that show no generic E. coli per 100mL.
      • Water used during growing activities must have test results that demonstrate a geometric mean of 126 or less colony forming units (CFUs) of generic E. coli per 100 mL of water and a statistical threshold value (STV) of 410 or less CFUs of generic E. coli per 100 mL of water. Please note that if you’re growing sprouts you have to meet the postharvest water threshold of zero generic E. coli per 100mL.
      • Harvest, postharvest, and hand washing water must have test results of zero generic E. coli per 100mL to be used.
      • Learn more about geometric mean and statistical threshold value here.
      • See tables below for specifics on testing frequency depending on source.
  4. Water testing method
    1. Currently, the FDA only recognizes one type of water testing method: Method 1603. Method 1603 is also referred to as, “Modified mTec” and uses the colony forming units (CFUs) methodology for measuring generic E. coli. It is extremely important that you confirm with the lab you use for your water testing that they are using Method 1603 in their analysis of colony forming units of generic E. coli. Currently, it is unclear whether tests that use other methods, such as most probable number (MPN), will be recognized by FDA.

Breakdown of water testing frequency:

Type of Agricultural Water
# of Tests to Develop Baseline
Baseline tests must be complete by:
# of Annual Tests after baseline is complete
Surface Water

(ex: irrigation ditches, ponds, creeks)

20 2020 – all other farms
2021 – for small farms
2022 – very small farms

(ex: well)

4 See above 1


All other farms: Gross more than $500K avg. over the last 3 years
Small Farms: Gross less than $500K avg. over the last 3 years
Very Small Farms: Gross less than $500K avg. over the last 3 years

Questions on agricultural water:

  • What if my water tests for water used during growing come back with a geometric mean above the 126 or less colony forming units (CFUs) of generic E. Coli per 100 mL of water and a statistical threshold value (STV) and/or above the 410 CFUs of generic E. Coli per 100 mL of water?

Answer: You have 3 options.

  • Stop using the water.
  • Treat the water.
    • There is currently no approved treatment methods for water used during growing.
  • Utilize the microbial die-off.
    • Pathogens die overtime in the natural environment from exposure to sun, wind, moisture, pH, etc. If your water doesn’t meet standard you can plan your last water before harvest to be a certain number of days before harvest aka the microbial die-off (depending on how far your water tests were from the allowable standard). Every day you wait from your last water to harvest provides a die-off rate of 0.5 log reduction. The law allows farmers to use up to 4 days for a microbial die-off. The FDA is working on creating a tool that allows users to type in their water test scores and then it will calculate the number of days you would have to wait to use the microbial die-off method.

2. How is a water source defined?

Answer: Each well is a source. If you get water from an irrigation ditch (or creek) and pull water from two different points along the ditch (or creek) you can count that as one source as long as there is no reasonable likelihood that the water was contaminated after you drew it from the first place along the ditch/creek and before you drew it from the second place along the ditch/creek.

3. I don’t know if my lab does the Method 1603 (CFU) for water test analysis?

Answer: Please contact your lab and ask them if they can do the 1603 method.

What lab do you use for your water tests? Let us know here and we’ll figure out if they do Method 1603. CAFF is currently making a list of California labs that do Method 1603 and MPN method. We will publish the list on our website sometime soon! Stay tuned.

4. If you have a question on anything on this page please email: foodsafety@caff.org and we’ll reach out to you as soon as possible.

This page draws from NSAC’s “Understanding the Produce Safety Rule” Publication and links from the Federal Register’s FSMA Codified language.

Updated 1/13/17.

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