In a large bowl mix water, cornstarch and eggs. On a plate or using a shaker bag mix breadcrumbs, onion and garlic powder.
Dip the shrimp into the cornstarch mixture until completely coated and then roll them in the bread crumb mixture. Stir the cornstarch batter, and then dip the shrimp back into the mixture and roll in breadcrumbs once more.
Deep fry shrimp in batches until golden brown. Drain on paper towels.