Some tips:
* Close the taps under your kitchen sink just before you sleep [this will not allow the cold water to fill up the tank over nite when the temprature could be lowest]
* There is some insluation protection for the water-pipes especially the ones reaching the water-tanks, its pretty cheap and can be a huge cost saver.
* you wont realise the pipe burst until the freeze is over, its only after that, when the roof starts to leak, the problem is realised.
* If you find a leak over in the roof but the floor above is not the final floor in the house [cos the water tanks are usualy in the last part of the floor]
* Check if there is any washer/water flowing thru the neck of the tap
* Keep that silicon filler handy at home [its very cheap], can do a temporary fix
* If you suspect the leak, as suggested, do close the knob under the kitchen-tap
* not only leaving the all taps open, do some flusing in the toilet to rapidly let go the water... basically another outlet to quicly empty the tank
Good luck!