5 replies to this topic

[L.M.R.]

We opened a new vegetable growing/harvesting facility just outside the city and therefore are using well water to water the crop. I test the water every month and last week had a positive test for total coliform. The count was low at 2 MPN/100mL but still failed under the local drinking water guidelines. I re-tested the next day and same result. We then shocked the well with chlorine and are now waiting on results from a third test.

Should we have ceased all watering activities after the first positive test? This would essentially have ruined the crop and all of our upcoming production. Has anyone had any experience with well water and positive tests for total coliform? Thanks

[Antores]

No necessarily. Coliforms are present in the environment, and depending of the water source, they are expected to be there. You need to remember that when testing for generic e-coli you are getting just an INDICATOR, finding generic e-coli doesn’t necessarily mean that the water is contaminated (or not).

With that said, other factor to consider is what is the water being used for? Is not the same if you are using it to drip irrigate a crop that for washing a product. In USA water contacting "post harvest" product (processing) shall meet drinking standards, and you said 2MPN meet drinking standards, so you should be fine.

I think what you need to do is have clear guidelines on what to test, what are the limits, and what to do (CAR) if the results are out of the limits. In the USA we do not have official performance standards for that,but must people are using the “California Leafy Green Standards”

The leafy green standards have different limits for water that contact product and water that does not contact product, as well as pre-harvest and podt-harvest. Based on that I made the standards for out water program and I’m attaching the chart below for your reference.

My recommendation for you is to go to the leafy Green Agreement,see their recommendations and use that information as a reference to make your own criteria limits.

For complete information go here: http://www.caleafygreens.ca.gov/food-safety-practices/downloads and open the LMGA Accepted Food Safety Practices 7/22/11 PDF Document.

Disclosure: This table what we use internally in our company (based on LMGA), and is id attached just as reference

 Water Parameters.png   22.94KB   37 downloads

Edited by Antores, 09 December 2011 - 06:32 PM.

[carine]

i was wondering why well (underground) water  will contaminated by E.coli? 

[Charles.C]

i was wondering why well (underground) water  will contaminated by E.coli? 

Dear carine,

 

Coliform likely not > E.coli

although E.coli usually > coliform.

 

Rgds / Charles.C

[Wine Gum]

Dear Carine

 

See the attached 2 documents on well water. Hope it will shed light on possible sources of the contamination  that you experience with your well (underground) water.

 

Regards

 

Makayla

Attached Files

•  gw1 - private wells.pdf   444.61KB   24 downloads
•  gw2 - drinking water from household wells.pdf   1.57MB   12 downloads

[Charles.C]

Dear Antores,

 

Thks for the excellent link.

 

I would comment that, based on a quick read, the acceptance criteria / frequency data in the neat table you included seemed not fully consistent with the reference document. ?

 

Rgds / Charles.C