Pour the water into the bottom of the Instant Pot. Place the steamer basket inside the Instant Pot and add the carrots and cauliflower.
Place a glass lid on top and set the timer for 15 minutes.
When the timer goes off, CAREFULLY lift the lid and use caution as the hot steam will escape quickly! Check for doneness by piercing the vegetables with a fork. They should be *almost* easy to pierce. Add additional cooking time, one minute at a time ONLY if necessary.
Add the broccoli and replace the lid. Set the timer for one minute.
When the timer goes off, remove the lid again and pierce the broccoli to check for doneness. Again, ONLY if necessary, add additional cooking time one minute at a time.