Chlorine bleach is a handy and powerful cleaning agent you can use around your home. But unlike many other cleaners, it has a relatively short shelf life. Here’s what you need to know.
If you’ve ever opened a bottle of bleach and been surprised that the room didn’t immediately smell like the pool at the YMCA, you’ve encountered a well-expired batch of bleach. To understand why your bottle of bleach smelled like nothing (or maybe very faintly like the beach instead of a swimming pool) you just need to look at the chemical composition of bleach.
The jug of chlorine bleach you bring home from the store is mostly water with enough chlorine (in the form of sodium hypochlorite) to create a concentration. That concentration depends on the brand and intended application, but it’s usually around 3-8% bleach. From the moment the mixture is bottled, it begins slowly breaking down. That breakdown turns the sodium hypochlorite into sodium chloride (table salt) and oxygen.
While the bleach will still smell like bleach for many months, it only takes around one year at room temperature (65-70°F) for the bleach to completely decompose into plain old salt water. At this point, you should dispose of it by pouring it down the drain in your laundry room or down the toilet and purchase a fresh bottle next time you’re at the store.