ZeroWater has a free recycling program through a partnership with a company called TerraCycle. Yep, free. You just sign up online, print a shipping label, and mail your used filters back. It’s like returning a library book, but you never have to speak to a librarian.
How To Dispose Of Zero Water Filters at Victoria Riley blog
If you don’t want to ship them, check your local recycling center. Some municipal facilities accept ion-exchange filters. Call first, or you’ll be the person showing up with a sad bag of filters and getting a confused look from the attendant.