Food Safety Education - Microbiology

FSMA Produce Safety Rule Grower Tools

The Produce Safety Rule (PSR) requires growers to initially establish a Microbial Water Quality Profile (MWQP) for each agricultural untreated surface water source. Growers must also conduct annual surveys for that water source in subsequent years.

The water quality profile is based on the levels of generic E. coli in your agricultural water. An initial MWQP must be established with a minimum of 20 water samples collected as close to harvest as possible over a period of at least 2 to a maximum of 4 years. Geometric mean (GM) and Statistical Threshold Value (STV) are calculated from these 20 samples (minimum). The GM and STV are your MWQP. The tools below compare your MWQP to the microbial water quality criteria stated in the Produce Safety Rule.

These tools were developed to make it easy to calculate the GM and STV and to determine if your water meets the standards for unrestricted application to produce before harvest. The tools were also designed to assist you with making food safety management decisions if your water does not meet the standards in the proposed rule.

Ag Water App and Related Resources:

  • Ag Water App (University of Arizona Coop. Ext.)
    Download onto any Wi-Fi enabled mobile device (Android, Apple, cell-phone, tablet, laptop) by visiting the Google Play or Apple app store. Type “Ag Water” in the search box and click download. Lastly, open the app and create your account with a username and password. All information added to the app is saved in your encrypted personal account and can be accessed from any device that you login to
  • Ag Water App Webpage (University of Arizona Coop. Ext.)
    An online version of the app, accessible from any device connected to the internet. Uses the same login information as the mobile app.
  • Online Calculator (University of Arizona Coop. Ext.)
    An online webpage accessible from any device connected to the internet. Data entered cannot be saved using the Online Calculator. Data can be printed for record keeping.
  • Excel Tool (Western Center for Food Safety, Version 4.0)
    Downloads as an Excel Spreadsheet (272 KB). This document can be saved to your device or a thumb drive.

More information on the Produce Safety Rule and agricultural water can be found by clicking on the following links:
FSMA Final Rule on Produce Safety
Standards for Growing, Harvesting, Packing, and Holding of Produce for Human Consumption
Quality Control of Wastewater for Irrigated Crop Production (FAO, United Nations)
Produce Safety, Audits, and Regulations A Few Short Question and Answers to Help Fruit and Vegetable Growers


Microbiology and Biofilm Intervention Food Safety Course

Welcome to the Microbiology and Biofilm Intervention Food Safety course brought to you by the University of Arizona Cooperative Extension. The Maricopa Agricultural Center and Yuma Agriculture Center have worked together to develop this curriculum to educate the food safety community on basic microbiology concepts, pathogenic contamination, current food safety research, and the importance of mitigating biofilms. Click on one of the links below and complete the lessons at your own pace. Thank you for participating!

Lesson 1 - Introductory Microbiology

Module 1 - Introduction to Microbiology
Module 2 - Pathogens
Module 3 - Pathogen Contamination

Lesson 2 - Intermediate Microbiology and Biofilms

Module 1 - Intermediate Microbiology
Module 2 - Food Safety Research & Application
Module 3 - Biofilm & Best Management Practices

**En Español aquí!**

If you run into any software problems while participating in our microbiology lessons, please send an email to:

Also please note that some issues may arise due to slow internet speeds. Good luck!