How to Put a Regular Mattress on a Waterbed Frame

Unplug the waterbed's heater.

Drain the water from the waterbed mattress. You may use an electric pump or simply attach a standard garden hose to the fill hole. Suck on the free end of the hose until water begins to flow. Put the hose in a sink or out the nearest window to allow it to drain the bed.

Remove the empty waterbed bladder. Clean up any spilled water with a sponge or towel.

Measure the length and width of the interior cavity to determine the size of the waterbed insert mattress. Waterbed frames that are 48 inches wide by 84 inches long require a Super Single insert. Frames that are 60-by-84 inches use California Queen inserts. A California King insert is 72-by-84 inches.

Purchase the appropriate insert according to the measurements taken in the previous step. Place the insert in the frame. Make the bed as normal. The insert has a 2-inch margin all the way around and accepts the same sheets and blankets as the original waterbed.