(Applicable unless State or Federal regulatory requirements dictate a higher or different standard or procedure for sampling or testing.)


  • The water system shall be informally mapped at a minimum. This allows for determining potential contamination risks. These risks include old wells, old irrigation systems, sources of water or the combination of sources, water flow, valves, returns and such all of which if damaged are potential sources of contamination. Water systems that are in close proximity which convey untreated water, contaminated water, human or animal waste need to be documented on the map to determine if cross contamination issues are present especially in flood conditions. This mapping allows for a risk analysis of the system for potential contamination issues.
  • The water system should be tested. Water has an appropriate microbiological quality for its intended use. The water shall be tested seasonally or at least annually if not of a municipal system.  The test should be conducted at the farthest point from the source as possible. For those systems that are heavily used the testing of many points on a more frequent basis is desirable. Tier III farms may have special schedules for water testing. Documentation of testing shall be retained a minimum of three years. See standard below.
  • Surface water has the potential for carrying a greater bacterial load after storms or other crisis, these should be analyzed for risk and water testing conducted.  Flooding and heavy rains are especially critical periods. Surface water is considered high risk.
  • Municipal water is tested by the city or state employing the system and for wells and other sources of water. Municipal water need not be tested if the regulatory source has issued a current report.
  • Water sources and systems that convey or are close to, or present a potential contamination hazard such as a feeding lot or industrial center must have a completely separate conveyance with little or no risk to irrigation water or water for human consumption. These water systems are considered high risk.
  • The storing of irrigation pipes, drip tape or other such conveyances must be stored and handled so to not increase the risk of contamination.
  • Reclaimed water shall be used in accordance with state and federal regulations.  Results of water tests shall be retained by the farmer for a period of three years.
  • Flooding or crisis situation where the water system is at high risk shall be evaluated using good risk analysis and appropriate remedial measure taken.
  • Tier III water applied to edible portions of the crop shall conform to the standard appropriate to the commodity.

Issues Bearing On the Use of Water

  • Upstream, open water, multi-distribution, multi-sourced or water-at-risk is evaluated for its risk potential.
  • Flooding is evaluated for its impact on the crop and irrigation system.
  • Irrigation methods and their potential effect on the edible portion of the crop are evaluated for risk.
  • Foliar applications will be appropriate for the commodity intended. See separate guidance.
  • The use of reclaimed water.

Best Practices

  • Known clear and clean source, timely and properly tested water conveyed to the field.
  • Proper application of the water to the commodity intended.
  • Appropriate microbiological standards for the commodity intended.

Water Standard 




Test Method



Tier 1: ≤ 235 MPN/100mL


Tier 2 and 3: ≤126 MPN/100mL

Pre-season, new harvest, new or renewed water system or upon other trigger issue.

High risk crops shall be tested IAW FDA guidance.

15 tube MPN (FDA BAM) or other U.S. EPC or AOAC, or other accredited method used for the assessment of bacteria in water. Laboratory shall be certified by the state.

Records maintained on site for a period not to exceed 3 years.

Note: Target Organism:generic E. coli. Sampling Procedure:100 mL sample collected aseptically at the point of use; i.e., one sprinkler head per water source for irrigation, water tap for pesticides, etc. Water utilized in pre-season irrigation operations may be tested and utilized.


  1. Tier I: (All Applications) Minimum requirement: a pre-season (preferred) or annual water test is required, on file with the farmer.  Generic E.coli: Negative
  2. Tier II (General Applications):
  • For any given water source (municipal, well, reclaimed water, reservoir or other surface water), samples for microbial testing shall be taken at a point as close to the point of use as practical (as determined by the sampler, to ensure the integrity of the sample, using sampling methods as prescribed below for Tier II) where the water contacts the crop, so as to test both the water source and the water distribution system. In a closed water system (meaning no connection to the outside) water samples may be collected from any point within the system but are still preferred as close to point of use as practical. No less than one sample per pre-season per distribution system is required under these standards unless a potential risk has occurred as described in the Tenants above. If there are multiple sources or sources defined as high risk, then samples shall be taken from different point-of-use locations monthly (randomize or rotate sample locations). Water for pre-harvest, direct edible portion contact shall meet or exceed microbial standards for recreational water over the course of the prescribed period. If only one sample has been taken, it must be below 126 CFU/100 mL. Once two samples are taken, a geometric mean can be calculated and the normal acceptance criteria apply. If the acceptance criteria are exceeded during this time period, additional samples may be collected to reach a 5 sample rolling geometric mean. The rolling geometric mean calculation starts after 2 samples have been collected. If the water source has not been tested in the past 60 days, the first water sample shall be tested prior to use, to avoid using a contaminated water source. After the first sample is shown to be within acceptance criteria, subsequent samples shall be collected no less frequently than monthly at points of use within the distribution system, if a risk situation applies. Ideally, pre-harvest water should not contain generic E. coli, but low levels do not necessarily indicate that the water is unsafe. A risk analysis and/or remedial action shall be taken when test results are higher than normal, or indicate an upward trend. Investigation and remedial action shall be taken when acceptance criteria are exceeded.
  • Remedial Actions:If the rolling geometric mean (n=5) or any one sample exceeds the acceptance criteria, then the water shall not be used whereby edible portions of the crop are contacted by water until remedial actions have been completed and generic E. coli levels are within acceptance criteria:
  • Conduct a risk analysis of the water source and distribution system to determine if a contamination source is evident and can be eliminated. Eliminate identified contamination source(s).
  • Credit is given to the California Leafy Green Marketing Agreement for some language used in this section.
3.  Commodity Specific:
    • As prescribed by Commodity Specific criteria.  This criteria may exceed the standards provided herein but cannot be less than those specified in any OPMA standard.
    • Certification of a Commodity Specific standard must meet the criteria specified by the authority prescribing that standard. 
    • Certification for compliance with the California, Arizona Leafy Green standard or other properly recognized standard must meet the criteria specified by the authority prescribing that standard. 
Major Non-Compliance
  • A single instance of contamination on edible portions of the crop,
  • A single instance of a positive or out-of-standard water test with no remedial action, 
  • Numerous instances where water has not been in compliance with any guideline in this standard or any state or federal applicable standard,
  • Any application of an input where the water is known to be contaminated,
  • Numerous incomplete, inadequate or inaccurate record keeping records or postings.
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