Does Household bleach expire?
Sodium hypochlorite decomposes continuously into sodium chloride and oxygen, faster when warm and faster still in light. A bottle a year old may have lost most of its available chlorine while smelling exactly the same, which matters because the smell comes from decomposition products rather than from the active ingredient. Anyone relying on bleach for disinfection — a water emergency, a food premises — is relying on a chemical with a genuine and quite short useful life. Most bottles carry a coded manufacture date rather than an expiry one.
How to store it
- Cool, dark cupboard. Not under a sink next to hot pipes.
- Never mix with ammonia or acid cleaners; both combinations produce toxic gas.
How to tell it has gone
- No reliable visual sign. Age from the manufacture code is the only guide.
"Use by" and "best before" are legally different. Use-by is a safety date and should be respected; best-before is about quality, and food is usually fine well past it. Where the two diverge matters, the page above says which applies.
Common questions
- Does Household bleach expire?
- It loses strength within months and eventually becomes salt water. This surprises most people.
- How long does Household bleach last?
- Full strength for about 6 months from manufacture; largely spent by 1 year
Related pages
- Does Eggs expire? Eggs stay usable for weeks past the date on the box, and the float test tells you about age rather than safety.
- Does Medicines expire? Most solid medicines keep much of their potency for years past the date — but a handful genuinely must not be used late.
- Does Petrol and diesel expire? Petrol goes stale within months, and ethanol blends go faster because they absorb water.
- Does Batteries expire? They self-discharge on the shelf, at very different rates by chemistry — and alkalines leak when flat.
- Does Wine expire? The great majority of wine is meant to be drunk within a year or two. Very little of it improves.
- Does Chocolate expire? It keeps far longer than the date. The white bloom on old chocolate is fat or sugar, not mould.
- Does Paint expire? Unopened water-based paint keeps a few years; opened tins depend entirely on how well they were sealed.
- Does Flour expire? White flour keeps 6-12 months; wholemeal goes rancid in 3-6 because the wheat germ oil oxidises.
- Does Honey expire? Does not expire
- Does Milk expire? Has a real expiry date
- Does Sunscreen expire? Unsafe or ineffective after the date
- Does Salt expire? Does not expire
- Does Frozen food expire? Indefinite if stored properly
- Does Canned food expire? Indefinite if stored properly
Sources
- US Environmental Protection Agency — EPA (Public domain (US Government))