;No, there are no electric heating elements in direct contact with the water inside the mattress. Instead, most heated waterbeds use an electric heating pad with a matrix of heating wires to warm the water. This would be like an electric blanket, including a thermostat to adjust the temperature. Most waterbed heaters start at 85 degrees F and can be adjusted in small increments. Some softside mattresses with pillow tops do not have heaters at all.