The same thing happened to me with my Mexican (now Lite) beer. I added over a gallon more water than needed- but it turned out to be a really refreshing brew- not watered down at all.
Live every day like it's brew day.
Bottled: Mexican "Lite" Cervesa, Blueberry Weizen, Pumpkin Ale, Clone-Harpoon 1991 Winter Warmer, Quaker Oatmeal Stout, Cranberry Zinger
Up Next: Hook & Ladder Red Ale