What is the difference between waterbed sheets and conventional sheets?
Waterbed sheets are two flat sheets attached at the center foot, and having triangular pockets sewn onto the corners of the bottom sheet to wrap around the waterbed mattress corners. The top sheet is attached to the bottom sheet since it would be difficult to tuck the top sheet under a heavy waterbed mattress, and attaching it keeps the top sheet from pulling loose. Conventional sheets, which are used on softside waterbeds in addition to innerspring, air, and foam beds, have a separate fitted bottom sheet and a flat top sheet.