Reverse Osmosis

Is reverse osmosis permitted to treat water used in organic food processing?

By Brian Baker

Reverse osmosis (RO) is a technique that moves water under pressure through a semi-permeable membrane to remove impurities. RO membranes are permeable to the water and impermeable to the impurities. These membranes are comprised of synthetic substances such as cellulose acetate or polyamides.

Because water is not an agricultural ingredient and is netted out of the organic content in processed food, RO treated water does not make water ineligible for use as an ingredient in an organic processed food. If anything, reverse osmosis may in fact remove impurities that would be unacceptable contaminants in organic food.

RO can also be used as a technique to concentrate flavors and enzymes. Natural flavors and enzymes are classified as nonagricultural by the National Organic Program and are listed on §205.605(a) as allowed nonorganic substances for use in processed organic products. This means that these substances do not have to be produced and processed organically in order to use them in organic foods.

Revised and updated in October 2016 by OMRI Technical Director Johanna Mirenda. This article was originally published in the Fall 2008 edition of the OMRI Materials Review newsletter.