[Kerry Irons]

Try it

Often I will make up 2 days worth of bottles at at time, for that days ride and the next days. Scoop of HEED, about 3/4 filled with water, shaken not stirred, stuck in fridge. Then just before riding I'll fill them up with ice.

Any reason they can't be mixed up like this even a week in advance? I could do something like 5 days of bottles at the same time which would be easier than one at a time.

Most likely you will be fine if you start with clean bottles. You would be willing to keep orange juice or Kool-Aid in the fridge for a week, yes? To be completely safe, put them in the freezer, but still probably OK in the fridge.