Combine oats, water, and salt in the bowl of a 6-quart pressure cooker (Instant Pot).
Secure lid and turn valve to “seal.”
Set on manual, high pressure, for 5 minutes. Once cook time has elapsed, let pressure release for 20 minutes. You do this by just leaving it alone! It has a timer that will count how much time has elapsed since it finished, but you can also set a timer if you think you’ll forget to check.
When 20 minutes has passed, turn valve to “vent” to release any remaining pressure.
Stir oats and serve with desired toppings.
Store leftovers in an airtight container and reheat in the microwave or in a small saucepan with a little milk if needed to thin the oatmeal.
If you prefer thinner oatmeal, use 6 cups of water.