Pour the water into the bottom of the Instant Pot, and arrange a trivet or steam basket over that. (I use the trivet that came with my machine.)
Poke the potatoes with a fork to vent, then place them on the trivet, keeping them out of the water. Secure the lid and move the steam release valve to Sealing.
Use the Manual or Pressure Cook button to cook at high pressure for 30 minutes. (This timing is based on using 6-ounce potatoes. Please refer to the post above to determine the correct timing based on the weight of potatoes that you have.) It will take roughly 10 minutes for the pot to come to pressure before the cooking cycle begins. (It will just say "On" until then.)
When the cooking cycle is complete, let the pressure naturally release for 10 minutes. When the screen reads LO:10, you can move the steam release valve to Venting to release any remaining pressure. When the floating valve in the lid drops, it's safe to open the lid.
Allow the potatoes to cool slightly, then slice them in half and serve warm with your favorite toppings. If you're not ready to serve the potatoes right away, you can use the "keep warm" setting on your Instant Pot to keep them warm until you're ready to eat.
Leftover potatoes can be stored in the fridge in an airtight container for up to a week.