Which side of the pillow do I sleep on? August 06, 2019 14:32 The pillow should be placed “cap down” against your mattress. Related articles Is normal tap water okay to use in the pillow? Chiroflow's Product Quality Assurance: What type of polyester filling is used in the Chiroflow pillow? How do my patients fill the pillow? What is the size of the Chiroflow® Professional Waterbase® pillow?