Precautions Fruit and Vegetable Growers Should Take During a Boil Water Advisory
Early this month, the Baltimore City Department of Public Works issued a Required Boil Water Advisory for parts of Baltimore City and a Precautionary Boil Water Advisory for a larger portion of the city and part of Baltimore County due to E. coli being identified in municipal water in parts of the city. While the Department of Public Works (DPW) has received the all-clear from the Mary-land Department of Environment to lift the boil water advisory, below are some tips for farmers in the event a similar event happens in the future.
What steps should farms in the affected area take to protect worker and customer health?
Farms in the affected region are encouraged to take precautions to protect farmer and customer health when using municipal water for worker hygiene, crop irrigation, and post-harvest washing. In most cases, it is probably impractical to boil all the water needed for farm operations. Instead, growers can either eliminate water contact with fruit and vegetables (and other food contact surfaces), or can treat the water with a food-safe sanitizer.
A factsheet on choosing a sanitizer is available from the Produce Safety Alliance, and a spread-sheet of sanitizer products is available for down-load from the UMD Produce Safety Team’s newsletter website (scroll down to week #32). If you use chlorine as a sanitizer, it is important to test the chlorine levels in the water to verify that you have achieved the correct concentration. An interactive online lab from New Mexico State University teaches growers how to do this correctly.
- Hand sanitizer does not work when hands are visibly dirty. You may choose to use an alcohol-based hand sanitizer AFTER washing hands with soap, potable (safe) water, and a paper towel. Remember, you cannot sanitize a dirty surface.
- We recommend buying potable drinking water, or boiling water, cooling it and then filling hand washing stations. If you boil water, re-member to bring water to a rolling boil for 1 minute. It is okay to boil water for 2 minutes if you’re not sure or lost count. Your farm can purchase a portable butane burner, electric induction stove top unit to quickly and efficiently boil water. It is still best to wash with soap and water first, to remove physical dirt, and then to use a hand sanitizer to kill any bacteria that might be on your hands.
- Avoid overhead irrigation with municipal water until the boil water advisory has been lifted. Growers can continue with drip irrigation methods where the water does not contact the edible portion of the plant.
- If you grow outdoors, we just got plenty of rain, so irrigation should not be necessary for about a week anyway.
- If you grow in a high tunnel or indoors and for some reason cannot drip irrigate, you should.
Post harvest washing:
- Do not use municipal water for post-harvest washing of fruits and vegetables until after the boil water advisory has been lifted. It would be better to not wash the vegetables at all.
What if you already overhead irrigated?
If you irrigated fruit or vegetable crops with municipal water since September 4, wait for four sunny days before you harvest the produce. This waiting period helps reduce the pathogen population.
Document, document, document!
Write down whatever precautions you take. If you use a sanitizer on water before using it for washing or irrigation, keep a record of the product label, how much you used per unit of water, and any verification steps you took (test strips for chlorine).
Baltimore City Department of Public Works: https://publicworks.baltimorecity.gov/node/22547
UMD Produce Safety website: https://extension.umd.edu/programs/family-consumer-sciences/food-safety-farm-table/produce-safety
UMD Extension Urban Agriculture website: https://extension.umd.edu/programs/agriculture-food-systems/program-areas/urban-agriculture