Does bleach expire? Yes, it starts degrading after 6 months (2024)

• Bleach expires after about a year, but it starts degrading after six months.
• If you use Clorox, you can find the expiration date on your bleach by searching for a two-line code on the bottle above the label.
• You should store bleach at room temperature and in a dark place to keep it from expiring sooner than the expiration date.
• This articlewas scientifically reviewedbyJosh Bloom, who holds a Ph.D. in chemistry, and is the director of chemical and pharmaceutical sciences at the American Council on Science and Health in New York.
• Visit Insider's Health Reference library for more advice.

Cleaning products usually accumulate in our under-sink cabinets over time, especially if we aren't cleaning as often as we probably should be. And if they're down their collecting dust for long enough, chances are some of them will expire.

Bleach, in particular, expires after about a year and becomes much less effective at disinfecting and killing germs. Here's what you need to know about how to store it, and how to tell if the bleach under your sink is still effective.

How long does bleach last?

Bleach is very effective for killing germs and viruses and disinfecting all sorts of surfaces around the home, but it's only effective if it isn't expired. Bleach typically lasts for about a year, says chemist Brian S. Leigh, PhD, a professor at University of California San Diego, Department of Chemistry and Biochemistry.

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.

When bleach degrades, it breaks down into water, salt, and oxygen, Leigh says. Therefore, it will not be effective for sanitizing whatever you'd like to sanitize.

How to tell if your bleach is expired

One of the surefire ways to know if your bleach is expired is if you open the bottle and you don't smell any kind of bleach odor, says Leigh. This is a sign that the bleach has degraded into a saltwater solution. If you open up a bottle and it still has a potent bleach smell, then it's likely that it will still disinfect.

Aside from the smell test, you can also reference the manufacturing date of the bleach, which can be found on a two-line code on Clorox bleach products, for example. This will be on the bottle above the label. The brand gives this example to decode the numbers to find the manufacturing date:

• If the code is A81421321CA3, you will use the third and fourth numbers to determine the last two numbers of the year it was manufactured. In this case, it's 14, which means 2014.
• After those two numbers will be the day of the year that the bottle was manufactured. In this case it's 213, which means it was made on the 213th day of 2014. That ends up being August 1st. (This isn't super easy to figure out on your own. You can use a chart like this to determine what day that would be.)

Use that date as a guideline to calculate an expiration date that's a year after the manufacturing date.

Clorox says that a year after the manufacture date should serve as your guideline when you're deciding if you should use the bleach you have or get new bleach, as long as you've been storing the bleach at room temperature.

How to store bleach

In order to prevent the bleach from degrading before its expiration date, you need to store it in the right environment.

Bleach should be stored:

• At room temperature (around 70ºF) or cooler
• In a dark place out of sunlight
• In its undiluted form (not mixed with water)

If you do happen to dilute bleach to use it for cleaning purposes, you should toss the solution out right after you use it because it will degrade much faster. Leigh says a diluted bleach and water solution can be rendered ineffective at disinfecting in just a few days to a week.

The bottom line

If your bleach isn't smelling like bleach or it's clearly been past a year since the manufacturing date, it's best to dispose of it and get new fresh bleach so you can rest assured that the bleach will be effective for cleaning and sanitizing.

Even when the bleach is old and likely degraded, you should not mix it with other cleaning products in an attempt to make an effective cleaning solution. Leigh says you should be careful to not cause any potentially dangerous chemical reactions. He suggests disposing of old bleach down the drain, and washing it down with plenty of water.

Learn more about how to kill germs with various disinfectants besides bleach.

Related stories about keeping germ-free:

• What temperature kills germs? How to use heat properly to get rid of bacteria and viruses
• Does bleach kill germs? Yes, but you need to let it sit for 10 minutes
• Does alcohol kill germs? Yes, as long as the solution is strong enough