Actually, you don't want to purchase sodium hypochlorite in bulk ("sodium chlorite" is a thing, but not what you are getting). Bleach, or sodium hypochlorite, breaks down rapidly at temperatures over 80 degrees, so it's best to store it where it is cool.

Recent changes in bleach manufacturing have improved the shelf life, but you still don't want to 'stock up' in May, for the August heat wave!