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 Can the pillow be washed? How much water should I use to start off? What is the size of the Chiroflow® Professional Waterbase® pillow? 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.