After the six-month expiration date, the sodium hypochlorite in bleach begins to degrade, at a rate of about 20 percent per year. Ultimately, due to the reaction of unstable ions, sodium hypochlorite (3NaOCl) breaks down into salt (2NaCl) and sodium chlorate (NaClO3), which is soluble in water.
Can you use expired bleach?
Bleach actually starts degrading, or breaking down, after about six months from the manufacture date. After six months, the bleach concentration will be less than when you first purchased it, but it will still be effective at disinfecting until a year has passed.
What can you do with old bleach?
Disposing of your bleach can be done easily in a few simple steps. Bleach can be poured down the kitchen sink or toilet, just as long as it's diluted with water. An even better way to get rid of your bleach is to give it away to someone else who needs it, such as a friend, family member, or local community center.