Bring water to a rolling boil in a saucepan. Add shell pasta and carrot shreds, allow them to boil, uncovered, for 10 minutes. Drain into a strainer and rinse under cold water.
In a medium-sized bowl, mix together the peas, the entire packet of ranch dressing mix, bacon bits, onion powder, and mayonnaise. Add pasta and carrots. Stir together until everything is coated with mayo-seasoning mixture. Chill and serve.