Wash and scrub the russet potatoes. Pierce each potato a few times using the tines of a fork.
Place a metal trivet at the bottom of the Instant Pot. Pour in the cup of water. Then place the russet potatoes on the trivet. Close the lid placing the valve to "sealing".
Select "manual" on high pressure for 12 minutes (for small), 14 minutes (for medium) and 16-18 minutes (for large). Once the timer is done let the Instant Pot come down to pressure for 10 minutes. Then, carefully force pressure. Using tongs, remove the potatoes out of the Instant Pot.
Using a fork, prick open the potato, fluff with the fork tines, top, and enjoy.