Which side of the pillow do I sleep on? Customer Service Desk August 06, 2019 14:48 Follow The pillow should be placed “cap down” against your mattress. Related articles How much water should I use to start off? What is the size of the Chiroflow® Professional Waterbase® pillow? Can the pillow be washed? Is normal tap water OK to use in my pillow? How long can the water stay in my pillow before it needs to be changed? Comments 0 comments Article is closed for comments.