In a large saucepan, cook the bacon until crisp. Remove the bacon, crumble, and set aside to use as a topping for the peas. Saute the onion in the bacon drippings until tender. Add the peas, diced tomatoes and green chiles, salt, chili powder, pepper and water. Cover and cook over medium heat for 45 minutes to 1 hour, or until the peas are tender. Add additional water, if necessary. Serve garnished with crumbled bacon.