Store bought bleach is typically around 6% Sodium Hypochlorite; NaClO. Once mixed with water, NaClO has a deterioration rate that gives it about a 6 month shelf life, even when sealed. After that it’s lost about 20% of its effectiveness (1-2% concentration) and maintains that for about a year. So storing commercial bleach solution long term isn’t possible. But there is an alternative.

Calcium Hypoclorite; Ca(ClO)2; is a shelf stable powder some of you might know better as Pool Shock. There are so many brands to choose from its insane. And until it comes in contact with water it has a shelf life of roughly 10 years. Though in theory its indefinite. A $2 pack of Pool Shock is enough (if I did the math right) to make 2 gallons of commercial strength bleach solution. If you go to a pool supply you might even find it in bulk resealable buckets.

If you want to go this route shoot for something thats roughly 70-75% Ca(ClO)2 by weight. With that concentration you can mix 2 tablespoons of pool shock with 3 cups warm water (for the love of god outside, it will put off chlorine gas) and have something around 6-8% concentration. Ta-Da…home made chlorine bleach.