“With a diameter of about 950 km (roughly the width of Spain, France, and Germany combined), Ceres is by far the largest and most massive body in the asteroid belt, and contains a third (32%) of the belt’s total mass.”
http://en.wikipedia.org/wiki/1_Ceres
In other words, the diameter of Ceres is about the distance between London and Marseilles, or roughly one end of France to the other. Not Spain France and Germany put together, unless you’re measuring them by their youthful waistlines. ;)
Try putting “40x more” than all the earth’s water on a rock the size of France.