Bring water to boil in a medium saucepan. Stir in couscous, and remove from heat. Cover, and let stand about 5 minutes, until liquid has been absorbed. Fluff with a fork.
In a large bowl, mix couscous and garbanzo beans. Toss in tomatoes and cucumbers. Stir olive oil and vinegar into the mixture. Season with garlic powder, salt, and pepper.
