honestly, you may have found a problem. i just looked on amazon and e bay, they both have food grade plastic gallon jugs, but the prices are retarded.....i was just thinking about using water jugs, as long as you keep using the same one for the same thing, i don't see why it would be a problem. light exposure is the only potential problem i can foresee, and that shouldn't be a big problem. just put a towel over it, or store it in a closet.