I looked up "coffee enema" and "why organic"
From a practical standpoint was the following:
In order for produce to be certified as organic in the U.S., it must pass strict requirements by an agency of the U.S. Department of Agriculture. For organic coffee beans, these requirements include proof of being grown in an area that is proven to have no exposure to prohibited pesticides and chemicals for at least 3 years. Additional requirements for certification include a sustainable crop rotation plan which avoids soil depletion and pest control through non-chemical methods.
So the question is not "why organic", the question is do want to risk the risk of direct contamination of chemically treated coffee beans that is not making it's way through the digestive process? (Not that that is any better)
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Retention time should be 15-20 minutes. 2-3 cups tops.