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May 11, 2021

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Breakfast with the Food Safety Group

Troubleshooting Deep Wells

Spring is usually the season when most farms are initiating water testing. Under both the Produce Safety Rule (PSR) and Good Agricultural Practices (GAP), a series of water tests can be a reassurance that a farm’s water source has a low risk of being the point of origin for pathogenic bacteria. If you have not tested your water source, here are some guidelines to get you started: 1. The PSFSG video on taking a water sample,, 2. Previous newsletter on well water sampling,[UNIQID].

What do you do if your well water sample comes back high in any of the required standards? The target parameters for potable water in Maryland are: total coliforms 0 or absent, turbidity < 10NTU and nitrates < 10mg/L.

Photo credit, Carol Allen

Hopefully, the farmer started with a water distribution system inspection. We often take for granted that our wells are protected from environmental pressures, but leaks in the piping, a displaced well head cover, a damaged sanitary seal and some missing bolts are a few of the more obvious points of entry into the well casing and the water below. What about the well casing? Is it free from cracks and obvious damage? The above-ground portion needs a visual inspection.
Nearby land use and topography can influence water potability. If the ground around the well head has sunken and rainwater can collect during a heavy storm or during snow melt, that standing water can be a source of pathogenic microbes. What is happening on your neighbor’s land? Are cattle or chickens being housed or grazed? We know that animal manure is a source of human pathogens. Is there a compost pile or dairy lagoon uphill from the well head? Has trash and debris been allowed to collect in the well head area? All of those issues can be obvious and correctable.

What about the less obvious sources of environmental intrusion? Is there a nearby abandoned well or septic system? Both of these previous uses of the area can contaminate a new well. Has the well been recently serviced? If the pump was pulled to the surface for servicing, it could have been contaminated before it was returned to the bottom of the well.

Photo credit, Carol Allen

If all of the above conditions check out, and the well pump has been recently pulled, shocking the well through the introduction of sodium hypochlorite (bleach) may be a good next step. The amount and type of bleach to use can be critical to its effectiveness. The fact sheet found here ( outlines the procedure.
Be sure to follow the directions exactly in calculating the amount and type of bleach to use and the length of time between application and the time of the first sample. Too much or too little sanitizer will either be a waste of time and money or simply not effective.

If a thorough inspection and shocking of the well does not produce the required results, a well system specialist needs to be employed. Your local agricultural agent can be a good source of guidance, or you can contact either Carol Allen (southern, central, and western Maryland) 240-994-5043, or Angela Ferelli, (Baltimore City, Cecil & Harford counties and Eastern shore) 302-353-7159, for help.

The Plant Science Food Safety Group YouTube Page!
Visit our website for more produce safety information
There are signs available through the MDA Food Quality Assurance Program to encourage good consumer practices while in the market and on the farm. Contact the Food Safety Group for availability.
This 12" x 18" poster comes either as a corrugated poster board or as a magnetic sign and is perfect for Pick-Your-Own operations.

Breakfast with the Food Safety Group from 7:00 - 10:00 am
We are offering virtual office hours from 7:00 - 10:00 am.
Carol Allen can be reached at 240-994-5043 on Monday, Wednesday & Friday mornings.
Angela Ferelli can be reached at 302-353-7159 Tuesday and Thursday mornings.
Call in with your questions about food safety for fresh produce.

Keep track of what is happening in produce safety and find cool resources. Check out our website: Food Safety Group Website 

Miss a back issue? They can be found on the website above by clicking on the "Food Safety Newsletter for Maryland Farmers" button. The past issues tab can be found in the top left corner.

Housekeeping: Notice there are Subscribe and Unsubscribe links at the bottom of the page. Please subscribe and pass this newsletter on! We want to serve your needs and the needs of all Maryland farmers big and small no matter your food crop. If something bugs you, please contact me! …but we want to stay in touch so don’t unsubscribe, reach out!

Carol D. Allen, Agent Associate and Editor
Chris Walsh, Professor Emeritus and Co-PI
University of Maryland
Plant Science Food Safety Group

Questions for MDA Food Quality Assurance Program:
Deanna Baldwin, Program Manager    

Food Quality Assurance Program
Maryland Department of Agriculture
Funding for this publication was made possible, in part, by the Food and Drug Administration through grant PAR-16-137.  The views expressed in written materials or publications and by speakers and moderators do not necessarily reflect the official policies of the Department of Health & Human Services; nor does any mention of trade names, commercial practices, or organization imply endorsement by the United States Government. University programs, activities, and facilities are available to all without regard to race, color, sex, gender identity or expression, sexual orientation, marital status, age, national origin, political affiliation, physical or mental disability, religion, protected veteran status, genetic information, personal appearance, or any other legally protected class
Highway 301 Fruit and Vegetable News
Department of Plant Science and Landscape Architecture Produce Safety
Carol D.Allen, Editor
Copyright © 2020 Plant Science Food Safety Group All rights reserved.

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