What is the yellow stuff on the end of the Microfilter membrane

The yellow material on the end of the microfilter membrane is a polyurethane potting compound. During manufacturing, this polyurethane is used to seal and secure the hollow fiber membranes at the ends of the filter. Its purpose is to hold the thousands of fibers firmly in place and prevent water from bypassing the filtration media.

The polyurethane is fully cured during production and is stable and safe for use in products that come into contact with drinking water. This material has been evaluated through third-party testing to meet applicable US FDA and EU regulatory requirements for food and drinking water contact materials.

Once cured, it does not migrate into the water under normal use and is considered safe for its intended purpose.