There are many misconception and myths surrounding the use of a water bed, including the idea that it does not provide sufficient back support. This misinformation appears to have its roots in the early days of the commercial water bed industry. Compared to the coil-spring construction of traditional orthopedic mattresses, a water bed's inner support system seemed much less supportive of the user's lumbar region. The belief among traditional mattress manufacturers was that a water bed did not hold the sleeper's body in proper alignment. They held that the long-term results of water bed sleeping would be more frequent back injuries.

In reality, the water bed has proven itself to be just as supportive as most coil spring mattresses. The heavy duty vinyl mattress of a water bed is usually compressed within the sturdy box frame. Various baffles and barriers can allow full wave action, semi-wave action or no wave action at all.

Some critics suggested that the full wave action of a water bed allowed the sleeper's lower back to sink dangerously low. In turn, this misalignment would create problems for the entire back. The effect would be similar to sitting in a formless beanbag chair for extended periods of time. Eventually, the lack of support would put too much stress on the joints and vertebrae.

One advantage of using a water bed is the addition of heat. Many modern water beds feature heating elements which can reach therapeutic temperatures. This heat can affect all of the muscles of the neck, back and hips equally. The compression of the water by the sleeper's body can also provide the same pressure point relief of traditional orthopedic mattresses. Earlier full wave water beds may have made the entry and dismount process trickier, but once the sleeper assumed a natural sleep position, he or she could still be supported by the weight of the water under compression.

A water bed may not receive universal approval from physicians for patients with chronic back problems, but neither is it the spine-twisting torture device some rival mattress companies portray it as in their literature. Supporters of heated water beds often mention their positive effects on back troubles caused by the sagging tendencies of other mattress systems.