Storage of Used RO Elements (Manual)

May 29, 2021


General Guidelines

TORAY RO elements must be preserved in a solution to prevent biological growth on membrane surfaces during storage and performance loss in a subsequent operation.
Element preservation is necessary for:
    •    Long term storage of new and used elements
    •    RO system shutdown ≥ 24 hours
If the RO elements have been in service, see “TMM-240 Shutdown considerations for RO systems” stated in “Toray RO Handling Manual”.

Storage of Used Elements

1.    Using RO permeate or softened water, prepare a 500–1,000 ppm sodium bisulfite solution. To prepare the solution, use food-grade sodium metabisulfite (SMBS). SMBS reacts with water to form sodium bisulfite (SBS) according to this reaction:

Na2S2O5 + H2O ==> 2 NaHSO3

2.    After soaking the elements for about 1 hour in the bisulfite solution, remove the elements and place them in a plastic oxygen barrier bag. Obtain oxygen barrier bags from Toray. Seal and label the bag(s), indicating the packaging date.

3.    Storage conditions for used/repackaged elements are the same as for new RO elements. See “Storage of New RO elements” of this section.

4.    When sending back used elements to Toray, please contact Toray or its representative before unloading elements.

The data and information contained in this document are based upon rigorous technical testing by Toray, and is to the best of our knowledge reliable. Toray cannot control design and operating conditions, and consequently Toray does not assume any liability for results obtained or damage incurred through the application of the information provided herein. No liability, warranty or guarantee of final product performance by Toray is implied by the information provided in this document.
This manual supersedes all previous versions. Technical modification of products or production technology may necessitate changes to information in this manual without prior notice. Please verify that your version of the manual is the latest version available by either contacting Toray, or checking online at

This content is extracted from Toray’s “Toray RO Handling Manual (Version. Apr. 2021)” (the Manual). Please refer to other contents stated in the Manual. When using this content, please read the Terms and Conditions of Use stated in the manual and agree to them before using this content.