You can run it with plain water, a few times. Fill the containers, and the unit, with water just below the C41 processing temperature. Set each step for 2-3 minutes, attach a drum, and run. Repeat until the discharged water is clear.
You don't need to attach it to a water supply to do this. Just fill the unit, plug it in, and go. It will also let you know if it reaches/maintains the proper temperature.