Just counting the bottles, soda intake in your household works out to 3350cc/day*person, on average. If you're not exaggerating, you have a very unhealthy habit.
Most of it is accounted for by two of us. My typical fluid intake is around 6000cc/day, including soda, coffee, bottled water, and tap water. The myfitnesspal site claims 2L of Coke Zero has 70 C, which would imply that a total (after coffee creamer) of ~200 C a day just from soda consumption. Apart from that it's just slightly acidic salt water, so I don't think I'd characterize it as "very" unhealthy. Perhaps "somewhat". :)