Place water in the inner pot, and then place the potatoes on the trivet and put inside the pot.
Close and lock the lid, turning the steam release valve to closed. Press Beans/Chili and adjust the time down to 18 minutes. (Or use "manual" high pressure and set to 18 minutes.) Press Start/Stop.
When the cooking cycle is done, allow a natural pressure release for at least 10 minutes. Release any remaining pressure by opening the steam release valve.
Remove potatoes to a plate, split open and fluff with a fork. Add butter, salt and pepper to serve.
If potatoes are not done to your liking (larger/thicker ones will take longer) simply replace the lid, Press Start/Stop to cancel the "Keep Warm" setting and then add more time. The pot will quickly preheat because it's already warm.
Make several potatoes by stacking them on top of each other, alternating directions if possible.
For the 8 or 10 quart pots, use 1 1/2 cups of water.