If the only water storage is in the toilet tanks, you'd better get the word out FAST not to flush. Get someone to hit all the restrooms and remove the handles or disable the auto-flush mechanisms (piece of duct tape over the sensor?).

People spread out in a large building is a waste of body heat. Get them together in a smaller room. Remember that couple that took 40 stranded travelers into their 1200 sqft home for three days during a blizzard? I'll bet they didn't need to burn much firewood.

With your mind on this subject, maybe it would be a good idea to approach the boss and suggest some pre-disaster plans and at least basic preps: food, water, possibly buckets/clip-on toilet seats, maybe a small locking refrigerator for medications like insulin.

Sue