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Anne Marie Helmenstine, Ph.D.

Chlorine Bleach Shelf Life

By January 31, 2014

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Chlorine Bleach (Mark Gallagher)Bleach is one of those household chemicals that loses its activity over time. It doesn't matter whether or not the bleach container has been opened or not. Temperature is the primary factor affecting how long bleach remains active.

According to Clorox™, the amount of hypochlorite that is added to their bleach depends on the season in which it is manufactured, because temperature affects the decomposition rate of sodium hypochlorite. So, more hypochlorite is added to bleach made in the summer than in cooler months. Clorox aims to maintain a 6% hypochlorite concentration for at least six months after the manufacturing date, assuming the bleach is stored around 70°F. It takes about 4-8 weeks from the time chlorine bleach is made to when it gets to a store so that you can buy it to take home. This leaves you 3-5 months where the bleach is at the effectiveness level stated on its label.

Does this mean bleach is useless after 3-5 months? No, because you probably don't need 6% hypochlorite for laundry and home disinfection. The 6% hypochlorite level is an EPA disinfection standard. If you store your bleach where it can get warmer than 70°F... like 90°F... the bleach is still effective for around three months.

So, when you buy a bottle of bleach, it has a shelf life. The bleach will be highly effective for around 6 months and fine for home use for around 9 months. If you're like me and have had the same bottle for a couple of years, it's probably time to go shopping.

How Bleach Works | Killing Power of Bleach & Vinegar


October 8, 2007 at 8:49 am
(1) Presbyterian Church of the Covenant NY says:

Thank you for this article. As I was cleaning our church, I thought I was going crazy because the bleach seemed to have the effectiveness of water. I told the Session that orders the supplies, but none of them had heard of bleach having an expiration date! Someone’s job was on the line because the place wasn’t getting clean, although he swore he was scrubbing. This article will probably save someone their job! Thanks so much.

October 8, 2007 at 9:52 am
(2) S. Castaneda, Denver says:

Very informative, however, what should we do with our old bleach. Going shopping isn’t the answer. Since the bleach has lost its effectiveness, is it safe to pour it down the drain?


October 8, 2007 at 12:12 pm
(3) W Faulk3 says:

Very useful data.
I have had a storm kit for 5 years.
I would like to find a something to replace the bleach. That has a long shelf life.
Anything else that may be in my supply kit??? about about first aid items.

thank you
Mobile, AL

October 9, 2007 at 8:58 am
(4) chemistry says:

Regarding what to do with old bleach… yes, pouring it down the drain probably is the best way to dispose of it. Sewer systems are equipped to handle it. If you have a septic tank system, don’t add a large volume of bleach all at once.

June 18, 2010 at 5:31 pm
(5) Dr David says:

Best Solution:
Don’t go buy more bleach, it is a toxic chemical, and you don’t need it in any way for cleaning. There are probably a dozen books on ways to clean your house withOUT using toxic chemicals, do a search at Amazon.com (I have no affiliation with them). You can try oxygen based bleachs, or light soap solutions or baking soda in water.

Especially if you have children, don’t use bleach nor Lysol around them, both are toxic for the liver (but Lysol is probably much worse). I am horrified when I see ads for a smiling Mom cleaning her infant’s food tray right in front of the infant with these toxic chemicals. Enjoy, hope this helped!

June 22, 2010 at 9:01 am
(6) Tom says:

Some important data and nice to know info was left out. When bleach breaks down, it’s an unstable chemical, it just turns into salt water. It breaks down at about 20% a year, so even after two years it’s still at about 3-4% strength and prefectly fine. Just don’t dilute it as much. And no need to throw it away.

The EPA standard for disinfection is .5% (think hospitals, doctor’s offices, laboratories), so if you start with 6% and dilute it the standard 10:1 you get .6%. That being close to the .5% requirement means it’s only “good” for a few days before no longer meeting the requirement. If you only do a 5:1 mix so 1.2%, it should be good for about 30 days. Don’t go over 2%.

The important point, that is for disinfection, and killing nasty bad germs. And once mixed, it quickly breaks down and should be replaced to maintain the standard. Distilled water is better. Tap water has organic particles in it that causes the bleach to break down faster.

For home use, don’t worry about it. Even 3-4 year old bleach is fine, just don’t dilute it as much. As for it’s “whitening” and cleaning ability, I have no idea. You certainly aren’t putting it in your laudry to disinfect it since you are dilutiting it way, way below .5%.

June 23, 2010 at 7:33 pm
(7) Bruce B. says:

You forgot to mention excess caustic in bleach. Since bleach decomposition produces acid, which furthers the decomposition rate, it can snowball. That’s why bleach manufacturers typical add a few molar percent excess caustic for stabilization. A great deal of the human toxicity due to bleach is because of the caustic as well as the hypochlorite itself. I think that’s worth noting.

August 29, 2010 at 11:36 pm
(8) JJ says:

I have water stored for emergencies…what am I to use for purifying this old water if not bleach??

October 17, 2010 at 12:57 pm
(9) RFEngineer says:

As a possible answer to those wanting to use bleach for emergency kit purposes:

Bleach can typically be made via electrolysis of a saturated saltwater solution (which is why it turns to salt water when it breaks down) By saturating water with salt, conducting electrolysis for a day, then boiling the solution until the water evaporates off, a powder forms at the bottom of the pan. That powder is a form of powdered bleach, and in powdered form, if kept dry, can be stored for a very long time. Mix about 200 grams of that with a gallon of water – and you have liquid bleach. Mix about 8 drops of that liquid bleach with water to purify it.

Please Ann – correct me if I am wrong!

November 10, 2010 at 7:16 pm
(10) LuLu40 says:

I have a question about the color of the bleach after it breaksdown, does it have a bleach odor,and what is the ph? I have an old bottle of bleach, I found in my Garage (at least I think it is bleach). It is clear, no bleach odor but a slight chemical smell and the ph is 7.5. I don’t want to dump it down the drain if someone used the bottle for something else. Thanks

March 13, 2011 at 12:52 pm
(11) Rick Maschek says:

Don’t ever mix bleach and any product containing ammonium as it can produce lethal chlorine gas. When I was with the fire department we got a call “man down in bathroom, gas present”. As funny as it seemed, the thought was chlorine and ammonium and sure enough, when we arrived the wife said he went down and she couldn’t get him out when the gas developed.
Don’t mix cleaning products.

April 23, 2011 at 10:36 am
(12) Sliceman says:

I have done some research about bleach for emergency preparedness and have found the following to be helpful. The Clorox bleach bottle has a very cryptic date stamp on it. You can find out from the stamp the date and time it was made.
The Clorox production date code will look something like this:

eg: A8815407

The first line goes like this plant/code/year/day/time/type

Plant = A8
Year = 8
Julian Date = 154 see a julian table = June 3rd
Time = 07
The second line includes information you dont need.

Using this information I keep the clorox bleach for 1 year from the date it is manufactured.

April 3, 2012 at 6:55 pm
(13) Dr. David says:

For emergency preparedness purposes, one teaspoon of bleach (not tablespoon) per gallon is what I’ve seen recommended, then let the bottle air out to get some of the chlorine out of it before drinking.

HOWEVER, why use toxic chemicals if you don’t need to? There are MULTIPLE different companies who now make drinking straws and small water bottles that completely remove any bacteria and parasites from fresh water from possibly polluted streams. Invest in them and you’re avoiding adding pollution to the planet as well as supporting new technology that is good for the environment, AND there is no shelf life on these bottles that purify, you can have them sitting in your basement for 20 years and still use them safely and effectively.

And lastly, for the person who has water stored in bottles in the basement (or where ever), if you screw on the tops without getting dirt into the bottles, the water should NOT need to be repurified! As long as it wasn’t polluted water to start with, you’re greater risk is from the plastic chemicals that will leach out of the bottle itself, not from the water. If the water is pure, it will not support the growth of bacteria or parasites, as they need something to feed on to reproduce and grow to where they would affect water quality. If there are a few thousand or even million bacteria when you seal the bottle, the pure water will cause them to explode due to osmosis making them absorb too much water, and they will die off.

January 25, 2013 at 9:28 pm
(14) jr23 says:

on the other compounds for purifying water one co recommends 5 ys from the date on package on the website it describes what to look for to see if older product is still good if unopened these are sold as tablets in sporting goods i believe there iodine for 1
any unopened should be good for 5 yrs there not that expensive throw away
there a newer system that uses a filter and 2 5 gallon buckets seems reasonable and there’s always boiling

February 4, 2013 at 12:12 pm
(15) yoyo says:

Dr. David….
You’re an idiot.

April 9, 2013 at 12:03 pm
(16) bio_guy says:

“Dr. David….
You’re an idiot.”

Yup, a real moron.

June 13, 2013 at 7:52 am
(17) Not as idiotic as yoyo says:

You are an even bigger idiot you troll.

You offer no constructive criticism or evidence of any kind to disprove anything Dr. David has said.

Please do the world a favor and drink your expired bleach bottle.

June 18, 2013 at 6:43 pm
(18) camper says:

Dr David’s recommendation may kill you.

The governments epa site recommends 1/8th of a teaspoon per gallon of water in emergency to make unknown water safe to drink.

To sterilize – which i do with my wine making equipment, I use 1/4 of a teaspoon, then rinse.

July 23, 2013 at 9:56 pm
(19) memememem says:

surprisingly, the EPA website recommends only EIGHT DROPS PER GALLON of bleach for disinfecting drinking water. (i always thought it was much higher!)

as far as shelf-life, if you replace it every six months it sounds like you’ll be fine from the above comments. but if you’re really tweaked about the exact efficacy level of your 6.1 month old bleach, then invest in a $10 bottle of disinfection tablets. that should keep you in potable water long enough for most of the zombies to die off.

another tip for storing water: algae needs light to grow, so cover your five gallon jugs with black plastic trash bags to inhibit growth. also, start with disinfected (bleached) water. remember, tap water is NOT sterile, which is why it grows stuff when left in a glass for a week.

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