Properly employed, a waterbed heater can create a wonderful, cozy sleeping experience. However, bear the following cautions in mind. Waterbed heaters usually take a day or two to heat up fully. Don't rush the heating process, or you could actually burst the waterbed and thus create a fire hazard. Advanced heaters won't allow you to speed up, anyway.

While heating your waterbed, you may want to add bedding on top to retain the energy produced by the heater. Don't stack too much on the bed, however, and strictly observe manufacturers' instructions and precautions. Usually, you can refer to a thermometer or at least an indicator light to find out when your bed is ready for use.

Waterbed heaters are usually made of rubber or vinyl. Old heaters may create what's called an Electromagnetic Field (EMF). Typically, this EMF won't cause any harm, but people with pacemakers or other electrically sensitive medical equipment should be aware of the EMF rating of their waterbed heater. You may want to consult a physician before using such a device.

Remember that waterbed heaters may not be appropriate for all sore muscle conditions. Waterbeds are not particularly firm, even when fully inflated. While heat tends to be soothing to sore muscles, you may want to speak with your doctor if you're suffering from a chronic condition. You should also make sure to unplug electrical components and waterbed accessories once you've finished heating your bed and to keep outlets away from places where water could leak out.