what you can do to make things a bit easier at work is use some cleaned out 1L or 2L plastic bottles or even gallon jugs and store the treated water in there.
that way, when you need to replace water in your tank at work, the water you have pretreated in the bottles/jugs are already (1) at room temperature and should be the same as the temp of the water in your office tank and (2) treated already. just pour in!
good luck.
