A waterbed mattress is a flexible vinyl bladder filled with water. Some waterbed mattresses are made up of water and fiber. The vinyl should be at least 20 millimeters thick; ideally it should be up to 27 millimeters thick, for increased durability and protection. The waterbed mattress can be of radial or "T" construction. Waterbed mattress radial construction involves two separate vinyl pieces being sewn together with the seams running around the outside edge of the mattress. With a waterbed mattress "T" construction one piece of vinyl is sewn at the top, the bottom and the middle, of the underside of the mattress, making seams form a "T" shape. A "T" constructed waterbed mattress lasts longer than a radial constructed mattress since it only has three exposed seams. Mattresses are stitched using a butt, single loop or double loop seam; with the latter supplying the greatest strength and durability.
Waterbed mattresses come in standard bed sizes: twin, double, queen, king and California king. They are also available in various types to meet different sleep needs.
Free flow mattress, or free float mattress, is a waterbed mattress that does not contain baffles or inserts to control the flow and wave action of the water.
The reduced motion mattress, or wave less mattress, is a waterbed mattress which contains fibers, baffles or cylinders to reduce the flow and wave action of the water. The reduction rate of the wave motion is measured as a percent. 40% reduced wave motion still provides a moderately wavy feel. 90% reduced wave motion offers very little wave motion, yet still supplies soft body contouring. Higher reduction rates indicate a waterbed mattress with less wave action and greater stability, firmness and support, especially when compared to free flow mattresses. For additional center support, look for a waterbed mattress which contains a lumbar support layer.
For further options, homeowners can choose from a single waterbed mattress or a dual waterbed mattress. A single waterbed mattress is one mattress within the waterbed frame. A dual waterbed mattress is two individual waterbed mattresses, combined into one mattress, within the waterbed frame. A dual mattress allows each sleeper to retain personal comfort levels.
The depth of the mattress is another important consideration in choosing a waterbed mattress. Mattresses start at 5 inches thick (shallow-fill), to 7 inches think (mid-fill) and finally can be thick as 10 inches (deep-fill). Generally speaking, the deeper the waterbed mattress the more comfort it provides.